Multiple kinesin family members expressed in teleost retina and RPE include a novel C-terminal kinesin.

Kinesins comprise a large superfamily of microtubule-based motor proteins, individual members of which mediate specific types of motile processes. To identify kinesin family members (KIFs) that are critical to retinal function and thus to vision, a reverse transcriptase polymerase chain reaction (RT-PCR) cloning strategy was used to isolate putative KIFs expressed in the neural retina and retinal pigmented epithelium (RPE) of the striped bass, Morone saxatilus. Eleven fish KIFs (FKIFs) were isolated from neural retina and six of the same FKIFs were also isolated from RPE. One of the KIFs identified in this screen, FKIF2, was the most prevalent clone detected both in the retina (41% of clones) and RPE (72% of clones). Based on predicted amino acid sequence homology within the motor domain, seven of the FKIFs have been tentatively assigned to known kinesin families: the kinesin heavy chain family (FKIF1, 5 and 9), the unc104/KIF1 family (FKIF3 and 8), the KIF2 family (FKIF4), and the cKIF family (FKIF2). Northern blot analysis revealed that each detectable FKIF exhibited a unique tissue-specific expression pattern. Since FKIF2 was more highly expressed in retina than in any other tissue tested, including brain, and was the most abundant KIF message expressed in both retina and RPE, it was examined in more detail and the complete approximately 2.3 kb open reading frame for FKIF2 was cloned and sequenced. The predicted amino acid sequence indicates that FKIF2 has a C-terminal motor domain, and thus is a member of the cKIF family. FKIF2 is only 36.5% identical at the amino acid level to the most closely related cKIF in the database, suggesting that FKIF2 may be a novel member of this family. Antibodies raised against a unique peptide specific to FKIF2 recognize an approximately 80 kd protein in homogenates of retina, RPE, brain and kidney. The pronounced expression of FKIF2 in retina and RPE suggests that FKIF2 may play an important role in microtubule-dependent motile events in these two tissues.