6J40 | pdb_00006j40

Structure of C2S2M2-type PSII-FCPII supercomplex from diatom

External Resource: Annotation

Domain Annotation: SCOP2 Classification
Domain Annotation: ECOD Classification
Gene Ontology: Gene Product Annotation
InterPro: Protein Family Classification
Membrane Protein Annotation: OPM

Domain Annotation: SCOP2 Classification SCOP2 Database Homepage

Chains	Type	Family Name	Domain Identifier	Family Identifier	Provenance Source (Version)
G [auth H]	SCOP2B Superfamily	Photosystem II 10 kDa phosphoprotein PsbH	8094731	3001547	SCOP2B (2022-06-29)
EA [auth h]	SCOP2B Superfamily	Photosystem II 10 kDa phosphoprotein PsbH	8094731	3001547	SCOP2B (2022-06-29)
P [auth V]	SCOP2B Superfamily	Cytochrome c	8094925	3000815	SCOP2B (2022-06-29)
NA [auth v]	SCOP2B Superfamily	Cytochrome c	8094925	3000815	SCOP2B (2022-06-29)
O [auth U]	SCOP2B Superfamily	PsbU/PolX domain-like	8094223	3000893	SCOP2B (2022-06-29)
MA [auth u]	SCOP2B Superfamily	PsbU/PolX domain-like	8094223	3000893	SCOP2B (2022-06-29)
M [auth O]	SCOP2B Superfamily	OMPA barrel-like	8095677	3000208	SCOP2B (2022-06-29)
KA [auth o]	SCOP2B Superfamily	OMPA barrel-like	8095677	3000208	SCOP2B (2022-06-29)

Domain Annotation: ECOD Classification ECOD Database Homepage

Chains	Family Name	Domain Identifier	Architecture	Possible Homology	Homology	Topology	Family	Provenance Source (Version)
I [auth J]	Bystin	e6j40J1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
GA [auth j]	Bystin	e6j40j1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
H [auth I]	Bystin	e6j40I1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
FA [auth i]	Bystin	e6j40i1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
G [auth H]	Bystin	e6j40H1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
EA [auth h]	Bystin	e6j40h1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
F	Bystin	e6j40F1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
DA [auth f]	Bystin	e6j40f1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
E	Bystin	e6j40E1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
CA [auth e]	Bystin	e6j40e1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
D	Bystin	e6j40D1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
BA [auth d]	Bystin	e6j40d1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
C	Bystin	e6j40C1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
AA [auth c]	Bystin	e6j40c1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
WA [auth 11]	Bystin	e6j40111	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
ZA [auth 14]	Bystin	e6j40141	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
YA [auth 13]	Bystin	e6j40131	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
XA [auth 12]	Bystin	e6j40121	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
OB [auth 38]	Bystin	e6j40381	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
NB [auth 37]	Bystin	e6j40371	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
MB [auth 36]	Bystin	e6j40361	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
LB [auth 35]	Bystin	e6j40351	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
KB [auth 34]	Bystin	e6j40341	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
JB [auth 33]	Bystin	e6j40331	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
IB [auth 32]	Bystin	e6j40321	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
HB [auth 31]	Bystin	e6j40311	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
DB [auth 18]	Bystin	e6j40181	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
CB [auth 17]	Bystin	e6j40171	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
BB [auth 16]	Bystin	e6j40161	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
AB [auth 15]	Bystin	e6j40151	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
U [auth W]	DUF5630	e6j40W1	A: alpha bundles	X: RNase A-like	H: Cytochrome P450	T: Cytochrome P450	F: DUF5630	ECOD (develop294)
SA [auth w]	DUF5630	e6j40w1	A: alpha bundles	X: RNase A-like	H: Cytochrome P450	T: Cytochrome P450	F: DUF5630	ECOD (develop294)
T [auth Q]	Bystin	e6j40Q1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
RA [auth q]	Bystin	e6j40q1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
Z [auth b]	Bystin	e6j40b1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
B	Bystin	e6j40B1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
S [auth Z]	Bystin	e6j40Z1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
QA [auth z]	Bystin	e6j40z1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
R [auth X]	Bystin	e6j40X1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
PA [auth x]	Bystin	e6j40x1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
Q [auth Y]	Bystin	e6j40Y1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
OA [auth y]	Bystin	e6j40y1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
P [auth V]	Bystin	e6j40V1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
NA [auth v]	Bystin	e6j40v1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
O [auth U]	Bystin	e6j40U1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
MA [auth u]	Bystin	e6j40u1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
N [auth T]	Bystin	e6j40T1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
LA [auth t]	Bystin	e6j40t1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
M [auth O]	Bystin	e6j40O1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
KA [auth o]	Bystin	e6j40o1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
L [auth M]	Bystin	e6j40M1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
JA [auth m]	Bystin	e6j40m1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
K [auth L]	Bystin	e6j40L1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
IA [auth l]	Bystin	e6j40l1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
J [auth K]	Bystin	e6j40K1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
HA [auth k]	Bystin	e6j40k1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
Y [auth a]	Bystin	e6j40a1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)
A	Bystin	e6j40A1	A: alpha bundles	X: Ten stranded beta/alpha barrel	H: Ten stranded beta/alpha barrel	T: Ten stranded beta/alpha barrel	F: Bystin	ECOD (develop294)

Gene Ontology: Gene Product Annotation Gene Ontology Database Homepage

Chains	Polymer	Molecular Function	Biological Process	Cellular Component
GA [auth j], I [auth J]	Photosystem II reaction center protein J	-	-	-
FA [auth i], H [auth I]	Photosystem II reaction center protein I	-	-	-
EA [auth h], G [auth H]	Photosystem II reaction center protein H	ion binding binding anion binding phosphate ion binding small molecule binding	regulation of protein stability biological regulation regulation of biological quality protein stabilization photosynthesis metabolic process cellular process	protein-containing complex photosystem intracellular anatomical structure photosystem II membrane membrane protein complex intracellular membraneless organelle intracellular organelle cellular anatomical structure organelle membraneless organelle photosynthetic membrane thylakoid chloroplast thylakoid membrane protein-containing complex photosystem intracellular anatomical structure photosystem II membrane membrane protein complex intracellular membraneless organelle intracellular organelle cellular anatomical structure organelle membraneless organelle photosynthetic membrane thylakoid chloroplast thylakoid membrane membrane-bounded organelle plastid membrane plastid organelle outer membrane plastid thylakoid membrane plastid thylakoid organelle envelope bounding membrane of organelle plastid envelope chloroplast intracellular membrane-bounded organelle thylakoid membrane chloroplast thylakoid outer membrane cytoplasm organelle membrane
DA [auth f], F	Cytochrome b559 subunit beta	-	-	-
CA [auth e], E	Cytochrome b559 subunit alpha	-	-	-
BA [auth d], D	Photosystem II reaction center protein D2	-	-	-
AA [auth c], C	Photosystem II chlorophyll protein CP43	-	-	-
GB [auth 21], RB [auth 41]	Fucoxanthin chlorophyll a/c-binding protein monomer 3	-	-	-
FB [auth 20], QB [auth 40]	Fucoxanthin chlorophyll a/c-binding protein monomer 2	-	-	-
EB [auth 19], PB [auth 39]	Fucoxanthin chlorophyll a/c-binding protein monomer 1	-	-	-
AB [auth 15], BB [auth 16], CB [auth 17], DB [auth 18], HB [auth 31], AB [auth 15], BB [auth 16], CB [auth 17], DB [auth 18], HB [auth 31], IB [auth 32], JB [auth 33], KB [auth 34], LB [auth 35], MB [auth 36], NB [auth 37], OB [auth 38], WA [auth 11], XA [auth 12], YA [auth 13], ZA [auth 14]	Fucoxanthin chlorophyll a/c-binding protein Lhcf1, FCP1	-	-	-
VA [auth 7], X [auth 2]	Unknown protein 2	-	-	-
UA [auth 6], W [auth 1]	Unknown protein 1	-	-	-
TA [auth 5], V [auth 0]	Unknown protein 0	-	-	-
SA [auth w], U [auth W]	Photosystem II reaction center protein W	-	-	-
RA [auth q], T [auth Q]	Extrinsic protein in photosystem II	-	-	-
B, Z [auth b]	Photosystem II chlorophyll protein CP47	-	-	-
QA [auth z], S [auth Z]	Photosystem II reaction center protein Z	-	-	-
PA [auth x], R [auth X]	Photosystem II reaction center X protein	-	photosynthesis metabolic process cellular process	protein-containing complex photosystem intracellular anatomical structure photosystem II membrane membrane protein complex intracellular membraneless organelle intracellular organelle cellular anatomical structure organelle membraneless organelle photosynthetic membrane thylakoid chloroplast thylakoid membrane protein-containing complex photosystem intracellular anatomical structure photosystem II membrane membrane protein complex intracellular membraneless organelle intracellular organelle cellular anatomical structure organelle membraneless organelle photosynthetic membrane thylakoid chloroplast thylakoid membrane membrane-bounded organelle plastid membrane plastid organelle outer membrane plastid thylakoid membrane plastid thylakoid organelle envelope bounding membrane of organelle plastid envelope chloroplast intracellular membrane-bounded organelle thylakoid membrane chloroplast thylakoid outer membrane cytoplasm organelle membrane
OA [auth y], Q [auth Y]	Photosystem II reaction center protein Ycf12	-	-	-
NA [auth v], P [auth V]	Cytochrome c-550	binding tetrapyrrole binding heme binding electron transfer activity cation binding transition metal ion binding iron ion binding ion binding metal ion binding small molecule binding	photosynthesis photosynthesis, light reaction metabolic process cellular process generation of precursor metabolites and energy cellular respiration energy derivation by oxidation of organic compounds respiratory electron transport chain electron transport chain	protein-containing complex photosystem intracellular anatomical structure photosystem II membrane membrane protein complex intracellular membraneless organelle intracellular organelle cellular anatomical structure organelle membraneless organelle photosynthetic membrane thylakoid chloroplast thylakoid membrane protein-containing complex photosystem intracellular anatomical structure photosystem II membrane membrane protein complex intracellular membraneless organelle intracellular organelle cellular anatomical structure organelle membraneless organelle photosynthetic membrane thylakoid chloroplast thylakoid membrane membrane-bounded organelle plastid membrane plastid organelle outer membrane plastid thylakoid membrane plastid thylakoid organelle envelope bounding membrane of organelle plastid envelope chloroplast intracellular membrane-bounded organelle thylakoid membrane chloroplast thylakoid outer membrane cytoplasm organelle membrane
MA [auth u], O [auth U]	Extrinsic protein in photosystem II	-	photosynthesis metabolic process cellular process regulation of biological process regulation of cellular process regulation of photosynthesis photosynthesis, light reaction photosystem II stabilization regulation of photosynthesis, light reaction biological regulation regulation of generation of precursor metabolites and energy generation of precursor metabolites and energy regulation of metabolic process	protein-containing complex photosystem intracellular anatomical structure photosystem II membrane membrane protein complex intracellular membraneless organelle intracellular organelle cellular anatomical structure organelle membraneless organelle photosynthetic membrane thylakoid extrinsic component of membrane
LA [auth t], N [auth T]	Photosystem II reaction center protein T	-	-	-
KA [auth o], M [auth O]	Extrinsic protein in photosystem II	-	photosynthesis protein-containing complex organization photosynthesis, light reaction generation of precursor metabolites and energy photosystem II assembly cellular component organization cellular component biogenesis cellular component assembly protein-containing complex assembly cellular process metabolic process cellular component organization or biogenesis regulation of biological process regulation of cellular process photosynthesis protein-containing complex organization photosynthesis, light reaction generation of precursor metabolites and energy photosystem II assembly cellular component organization cellular component biogenesis cellular component assembly protein-containing complex assembly cellular process metabolic process cellular component organization or biogenesis regulation of biological process regulation of cellular process regulation of photosynthesis photosystem II stabilization regulation of photosynthesis, light reaction biological regulation regulation of generation of precursor metabolites and energy regulation of metabolic process	protein-containing complex photosystem intracellular anatomical structure photosystem II membrane membrane protein complex intracellular membraneless organelle intracellular organelle cellular anatomical structure organelle membraneless organelle photosynthetic membrane thylakoid
JA [auth m], L [auth M]	Photosystem II reaction center protein M	-	-	-
IA [auth l], K [auth L]	Photosystem II reaction center protein L	-	-	-
HA [auth k], J [auth K]	Photosystem II reaction center protein K	-	-	-
A, Y [auth a]	Photosystem II reaction center protein D1	-	-	-

InterPro: Protein Family Classification InterPro Database Homepage

Chains	Accession	Name	Type
EA [auth h], G [auth H]	IPR036863	Photosystem II reaction centre protein H superfamily	Homologous Superfamily
EA [auth h], G [auth H]	IPR001056	Photosystem II reaction centre protein H	Family
RA [auth q], T [auth Q]	IPR023222	PsbQ-like domain superfamily	Homologous Superfamily
PA [auth x], R [auth X]	IPR009518	Photosystem II PsbX	Family
PA [auth x], R [auth X]	IPR023431	Photosystem II PsbX, type 1 subfamily	Family
NA [auth v], P [auth V]	IPR017851	Photosystem II extrinsic protein V, cytochrome c-550 precursor	Family
NA [auth v], P [auth V]	IPR016003	Photosystem II extrinsic protein V, cytochrome c-550 precursor-like	Family
NA [auth v], P [auth V]	IPR036909	Cytochrome c-like domain superfamily	Homologous Superfamily
NA [auth v], P [auth V]	IPR009056	Cytochrome c-like domain	Domain
NA [auth v], P [auth V]	IPR029490	Cytochrome c-550 domain	Domain
MA [auth u], O [auth U]	IPR010527	Photosystem II PsbU, oxygen evolving complex	Family
KA [auth o], M [auth O]	IPR011250	Outer membrane protein/outer membrane enzyme PagP, beta-barrel	Homologous Superfamily
KA [auth o], M [auth O]	IPR002628	Photosystem II extrinsic protein O	Family

Membrane Protein Annotation: OPM OPM Database Homepage

Chains	External Link	Type	Class	Superfamily	Family
EA [auth h], G [auth H], KA [auth o], M [auth O], MA [auth u] EA [auth h], G [auth H], KA [auth o], M [auth O], MA [auth u], NA [auth v], O [auth U], P [auth V], PA [auth x], R [auth X], RA [auth q], T [auth Q]	OPM	Transmembrane	Alpha-helical polytopic	Photosystems	Photosystem II