title: Identification and characterization of photomedins: novel olfactomedin-domain-containing proteins with chondroitin sulphate-E-binding activity.
abstract: We screened more than 60000 RIKEN mouse cDNAs for novel ECM (extracellular matrix) proteins by extensive computational screening followed by recombinant expression and immunohistochemical characterization. We identified two novel olfactomedin-family proteins characterized by the presence of tandem CXCXCX9C motifs in the N-terminal region, a coiled-coil domain and an olfactomedin domain in the C-terminal region. These proteins, named photomedin-1 and photomedin-2, were secreted as disulphide-bonded dimers (photomedin-1) or oligomers/multimers (photomedin-2) with O-linked carbohydrate chains, although photomedin-1 was proteolytically processed in the middle of the molecule after secretion. In the retina, photomedin-1 was selectively expressed in the outer segment of photoreceptor cells and photomedin-2 was expressed in all retinal neurons. Among a panel of ECM components, including glycosaminoglycans, photomedins preferentially bound to chondroitin sulphate-E and heparin. These results, together, indicate that photomedins are novel olfactomedin-domain-containing extracellular proteins capable of binding to proteoglycans containing these glycosaminoglycan chains.
authors.affiliation: Sekiguchi Biomatrix Signaling Project, Exploratory Research for Advanced Technology (ERATO), Japan Science and Technology Agency, Aichi Medical University, Nagakute, Aichi, 480-1195, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Furutani
authors.forename: Ri-ichiroh
authors.initials: R
authors.lastname: Manabe
authors.forename: Ko
authors.initials: K
authors.lastname: Tsutsui
authors.forename: Tomiko
authors.initials: T
authors.lastname: Yamada
authors.forename: Nagisa
authors.initials: N
authors.lastname: Sugimoto
authors.forename: Shiro
authors.initials: S
authors.lastname: Fukuda
authors.forename: Jun
authors.initials: J
authors.lastname: Kawai
authors.forename: Nobuo
authors.initials: N
authors.lastname: Sugiura
authors.forename: Koji
authors.initials: K
authors.lastname: Kimata
authors.forename: Yoshihide
authors.initials: Y
authors.lastname: Hayashizaki
authors.forename: Kiyotoshi
authors.initials: K
authors.lastname: Sekiguchi
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D011508:Chondroitin Sulfate Proteoglycans / Q000737:chemistry*; D016326:Extracellular Matrix Proteins / Q000737:chemistry*; D005136:Eye Proteins / Q000737:chemistry* / Q000378:metabolism; D006023:Glycoproteins / Q000737:chemistry*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D012160:Retina / Q000737:chemistry*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D011508:Chondroitin Sulfate Proteoglycans; D016326:Extracellular Matrix Proteins; D005136:Eye Proteins; D006023:Glycoproteins; C081451:olfactomedin