DISTRIBUTION PATTERN OF 3 NEURAL CALCIUM-BINDING PROTEINS (NCS-1, VILIP AND RECOVERIN) IN CHICKEN, BOVINE AND RAT RETINA

Neural Ca2+-binding proteins (NCaPs) constitute a subfamily of 4-EF-ha nd proteins, and display a histological and structural dichotomy: the A-type NCaPs are selectively expressed by the retina and pineal organ and display two canonical EF-hands, whereas the B-type NCaPs are found in the entire brain and present three regular EF-hands. In this study , antisera were raised against the A-type NCaP recoverin (26 kDa) and the B-type NCaPs VILIP and NCS-1 (22 kDa). Since the sequence identity among NCaPs is high, specific polyclonal antibodies were purified by double cross-immunoaffinity chromatography; both ELISA and immunoblot analyses determined that the resulting antibodies showed selectivity r atios inferior to 1/363 for the two other related NCaPs. Besides, the anti-VILIP antibodies displayed some affinity toward neurocalcin delta , and the anti-recoverin antibodies recognized a 24 kDa protein, which is most likely visinin. Thus, immunohistochemical studies on the chic ken, rat and cow retina revealed that anti-recoverin antibodies recogn ized the vertebrate photoreceptors and a small number of mammalian bip olar cells. Anti-VILIP antibodies exclusively labelled the inner retin a, i.e. the amacrine and ganglion cells. NCS-1 was mainly present in t he photoreceptor inner segments, the inner plexiform layer and the gan glion cells. NCS-1 showed the highest species disparity. The retinal l ocalization of NCS-1 and VILIP offered an important morphological basi s for the understanding of their function. Furthermore, specific antib odies against the NCaPs may enable the identification of cell populati ons in more complex neural tissues, such as the brain.