Interphotoreceptor matrix in the fovea and peripheral retina of the primate Macaca mulatta: Distribution and glycoforms of SPACR and SPACRCAN

SPACR and SPACRCAN localization in the interphotoreceptor matrix (IPM) of t he fovea and peripheral retina of Macaca mulatta was established with antib odies to these core proteins and the chondroitin sulfate epitopes and lecti n binding properties of these molecules were defined. The IPM of both rods and cones labeled with anti-SPACR, anti-SPACRCAN, anti-Delta Di6S antibodie s and wheat germ agglutinin (WGA). Whereas anti-SPACR and anti-SPACRCAN ant ibodies labeled rod and cone matrix compartments with similar intensity, th e Delta Di6S chondroitin antibody labeling was more intense around cones th an rods. Peanut lectin (PNA) labeling was present only around cones. No IPM labeling was observed with Delta Di0S-chondroitin or Delta Di4S-chondroiti n antibodies. Western blots of undigested IPM extracts showed anti-SPACR im munoreactivity at 150 kDa, colocalizing with the position of WGA and PNA bi nding. In Western blots of the chondroitinase ABC digested sample and sampl es double digested with chondroitinase ABC and AC II. anti-SPACR immunoreac tivity, WGA and PNA labeling intensity were virtually identical to that in the undigested sample, with prominent staining of the 150 kDa SPACR band. I n contrast, anti-SPACRCAN immunoreactivity was not present in the undigeste d sample, but was evident in both the chondroitinase ABC and double digeste d samples as a broad band at approximately 230 kDa. Delta Di6S, Delta Di4S, WGA and PNA labeling colocalized with the anti-SPACRCAN immunoreactivity i n the chondroitinase ABC digested sample. These findings indicate that SPAC R and SPACRCAN are present around cones in the fovea and both rods and cone s in the peripheral retina, but that the specific glycoforms of these molec ules are different depending on whether present in the cone or rod associat ed IPM. (C) 2000 Academic Press.