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The presence of a soluble interphotoreceptor retinol‐binding protein (IRBP) in the retinal interphotoreceptor space
Author(s) -
Pfeffer B.,
Wiggert B.,
Lee L.,
Zonnenberg B.,
Newsome D.,
Chader G.
Publication year - 1983
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.1041170308
Subject(s) - retinol binding protein , extracellular , retinal , biochemistry , chemistry , retinal pigment epithelium , glycoprotein , intracellular , binding protein , visual phototransduction , retinol , gel electrophoresis , retina , biology , vitamin , neuroscience , gene
Abstract A new, gentle technique has been developed for washing of the retinal interphotoreceptor space (IPS) to obtain soluble components of the extracellular matrix (ECM). Using this method, we have determined that the major soluble coustituent of monkey IPS is a 146,000 M r glycoprotein, which binds [ 3 H]retinol, sediments on sucrose gradients at 7S and has an R f of 0.42 on native gel electrophoresis. Using size‐exclusion high performance liquid chromatography, the apparent molecular weight of the native protein was calculated to be 250,000 daltons. In contrast to previous studies, no 15,000‐dalton cellular retinol‐binding protein (CRBP) or 33,000‐dalton cellular retinaldehydebinding protein (CRALBP) was observed in the IPS wash, indicating that these proteins are probably not involved in retinol transport between retina and pigment epithelium (PE). In the supernatant fraction of retinal homogenates that contains soluble intracellular proteins as well as extracellular constituents, the 146,000 M r protein was closely associated with a 93,000 M r protein that could be separated on SDS‐gel electrophoresis; the 93,000 M r protein was not found in the IPS wash. The 146,000 M r interphotoreceptor retinol‐binding protein (IRBP) may function in extracellular retinol transport in the IPS.