The presence of a soluble interphotoreceptor retinol-binding protein (IRBP) in the retinal interphotoreceptor space
✍ Scribed by B. Pfeffer; B. Wiggert; L. Lee; B. Zonnenberg; D. Newsome; G. Chader
- Publisher
- John Wiley and Sons
- Year
- 1983
- Tongue
- English
- Weight
- 913 KB
- Volume
- 117
- Category
- Article
- ISSN
- 0021-9541
No coin nor oath required. For personal study only.
✦ Synopsis
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 constituent of monkey IPS is a 146,000 M, glycoprotein, which binds [3H]retinol, sediments on sucrose gradients at 7s and has an Rf 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 t h e 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, protein was closely associated with a 93,000 M, protein that could be separated on SDS-gel electrophoresis; the 93,000 M, protein was not found in the IPS wash. The 146,000 M, interphotoreceptor retinolbinding protein (IRBP) may function in extracellular retinol transport in the -.
IPS.