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interphotoreceptor matrix proteoglycan 2 (sialoprotein associated with cones & rods proteoglycan, Spacrcan, interphotoreceptor matrix proteoglycan of 200 kD, IPM 200) (IMPG2 IPM200)
Function:
- chondroitin sulfate- & hyaluronan-binding proteoglycan involved in organization of interphotoreceptor matrix
- may participate in the maturation & maintenance of the light-sensitive photoreceptor outer segment
- binds heparin
Structure:
- highly glycosylated (N- & O-linked carbohydrates)
- contains 2 EGF-like domains
- contains 2 SEA domains
Compartment: membrane
Expression:
- expressed in the retina
- pressed by photoreceptors of the interphotoreceptor matrix surrounding both rods & cones
- detected in the pineal gland
Polymorphism:
- variations in IMPG2 coding region are implicated in inherited retinopathies
General
membrane protein
proteoglycan
receptor
Properties
SIZE: entity length = 1241 aa
MW = 139 kD
COMPARTMENT: cellular membrane
MOTIF: signal sequence {1-22}
N-glycosylation site {N154}
Thr glycosylation site {T190}
Thr glycosylation site {T192}
SEA domain {234-356}
MOTIF: binding site
SITE: 259-267
FOR-BINDING-OF: hyaluronate
N-glycosylation site {N301}
N-glycosylation site {N320}
N-glycosylation site {N370}
Thr glycosylation site {T544}
Thr glycosylation site {T556}
SEA domain {892-1011}
MOTIF: N-glycosylation site {N942}
N-glycosylation site {N956}
EGF domain {1010-1051}
MOTIF: cysteine residue {C1014}
MODIFICATION: cysteine residue {C1025}
cysteine residue {C1019}
MODIFICATION: cysteine residue {C1036}
cysteine residue {C1025}
MODIFICATION: cysteine residue {C1014}
cysteine residue {C1036}
MODIFICATION: cysteine residue {C1019}
cysteine residue {C1038}
MODIFICATION: cysteine residue {C1050}
cysteine residue {C1050}
MODIFICATION: cysteine residue {C1038}
EGF domain {1052-1093}
MOTIF: cysteine residue {C1054}
MODIFICATION: cysteine residue {C1067}
cysteine residue {C1061}
MODIFICATION: cysteine residue {C1077}
cysteine residue {C1067}
MODIFICATION: cysteine residue {C1054}
cysteine residue {C1077}
MODIFICATION: cysteine residue {C1061}
cysteine residue {C1079}
MODIFICATION: cysteine residue {C1092}
binding site
SITE: 1080-1088
FOR-BINDING-OF: hyaluronate
cysteine residue {C1092}
MODIFICATION: cysteine residue {C1079}
transmembrane domain {1100-1120}
binding site
SITE: 1125-1133
FOR-BINDING-OF: hyaluronate
binding site
SITE: 1136-1145
FOR-BINDING-OF: hyaluronate
binding site
SITE: 1210-1218
FOR-BINDING-OF: chondroitin sulfate
Database Correlations
OMIM 607056
UniProt Q9BZV3
Pfam PF01390
Kegg hsa:5093
References
UniProt :accession Q9BZV3
Components
hyaluronate; hyaluronic acid; hyaluronan
proteoglycan core protein
proteoglycan link protein; cartilage link protein