Identification and characterization of photomedins: novel olfactomedin-domain-containing proteins with chondroitin sulphate-E-binding activity.
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.
Furutani
Yutaka
Y
Sekiguchi Biomatrix Signaling Project, Exploratory Research for Advanced Technology (ERATO), Japan Science and Technology Agency, Aichi Medical University, Nagakute, Aichi, 480-1195, Japan.
Manabe
Ri-ichiroh
R
Tsutsui
Ko
K
Yamada
Tomiko
T
Sugimoto
Nagisa
N
Fukuda
Shiro
S
Kawai
Jun
J
Sugiura
Nobuo
N
Kimata
Koji
K
Hayashizaki
Yoshihide
Y
Sekiguchi
Kiyotoshi
K
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
D011508:Chondroitin Sulfate Proteoglycans; D016326:Extracellular Matrix Proteins; D005136:Eye Proteins; D006023:Glycoproteins; C081451:olfactomedin