Molecular cloning and characterization of chick sialoprotein associated with cones and rods, a developmentally regulated glycoprotein of interphotoreceptor matrix.
MY-174 is an IgM class monoclonal antibody originally established against chick PG-M/versican. The antibody specifically stains the photoreceptor layer, where we recently reported an absence of PG-M/versican. In this study, we re-characterized the antibody and identified the molecule that reacts to MY-174 at the photoreceptor layer. Immunohistochemistry localized the antigen to the matrix surrounding photoreceptors. A variety of glycosidase digestions showed that the antigen is the 150-kDa glycoprotein that has sialylated N- and O-linked glycoconjugates having a molecular mass of more than 30-kDa. The peptide sequences obtained from purified MY-174 antigen showed we had sequenced a full-length cDNA with an open reading frame of 2787 base pairs, encoding a polypeptide of 928 amino acids, with 56 and 54% identities to human and mouse sialoprotein associated with cones and rods (SPACRs), respectively, and with the structural features observed in SPACRs. The specific sialylated O-glycoconjugates here are involved in the epitope structure for MY-174. SPACR first appeared by embryonic days 15-16, and expression increased with developmental age, paralleling the adhesion between neural retina and retinal pigment epithelium. Thus, we concluded that the MY-174 antigen at the photoreceptor layer, a developmentally regulated glycoprotein, is identical to chick SPACR and may be involved in a novel system mediating adhesion between neural retina and retinal pigment epithelium.
Zako
Masahiro
M
Department of Ophthalmology, Aichi Medical University, Nagakute, Japan. zako@aichi-med-u.ac.jp
Iwaki
Masayoshi
M
Yoneda
Masahiko
M
Miyaishi
Osamu
O
Zhao
Jinsong
J
Suzuki
Yasuhiko
Y
Takeuchi
Makoto
M
Miyake
Goichiro
G
Ikagawa
Hiroshi
H
Kimata
Koji
K
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002642:Chick Embryo; D003001:Cloning, Molecular; D018076:DNA, Complementary; D016326:Extracellular Matrix Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D005136:Eye Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D008856:Microscopy, Fluorescence; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D011509:Proteoglycans; D017386:Sequence Homology, Amino Acid; D012795:Sialoglycoproteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism
D018076:DNA, Complementary; D016326:Extracellular Matrix Proteins; D005136:Eye Proteins; C486429:IMPG1 protein, mouse; D011509:Proteoglycans; D012795:Sialoglycoproteins