Characterization of a novel C-kinesin (KIFC3) abundantly expressed in vertebrate retina and RPE

Many forms of intracellular transport are mediated by microtubule-dependent motors of the kinesin superfamily (KIFs), To identify kinesins expressed i n human retina and RPE, we used degenerate primer RT-PCR to amplify a simil ar to 440 bp kinesin motor domain fragment from human retinal and RPE messe nger RNAs. Four distinct kinesins were detected: one C-kinesin (HsKIFC3); o ne kinesin from the unc104/KIF1 family [HsKIF1A]; and the ubiquitous and ne uronal forms of conventional kinesin heavy chain [HsuKHC and HsnKHC]. The C -kinesin HsKIFC3 comprised 33.3% of the retinal clones and was 60% identica l to FKIF2, the most abundant kinesin detected in a previous screen of fish retina and 95% identical to a fragment of MmKifC3 recently amplified from mouse brain. Elsewhere we have reported the sequence of HsKIFC3 and shown t hat it maps to the same locus on chromosome 16q13-q21 as Bardet-Biedl syndr ome Type II, a hereditary retinal degeneration. We describe here the kinesi n PCR screen of human retina and RPE and examine the tissue and subcellular distribution of KIFC3 in both fish and human retina using an antibody rais ed against a peptide conserved between FKIF2 and HsKIFC3. This peptide anti body identified a single similar to 80 kDa band in Western blots of fish an d human retina and RPE. In both fish and human retina this antibody strongl y labeled photoreceptor terminals in the outer plexiform layer, suggesting that FKIF2/KIFC3 may play some role in the photoreceptor synapse. (C) 1999 Academic Press.