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 prote ins, individual members of which mediate specific types of motile proc esses. To identify kinesin family members (KIFs) that are critical to retinal function and thus to vision, a reverse transcriptase polymeras e chain reaction (RT-PCR) cloning strategy was used to isolate putativ e 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, w as the most prevalent clone detected both in the retina (41% of clones ) and RPE (72% of clones). Based on predicted amino acid sequence homo logy within the motor domain, seven of the FKIFs have been tentatively assigned to known kinesin families: the kinesin heavy chain family (F KIF1, 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 expressio n pattern, Since FKIF2 was more highly expressed in retina than in any other tissue tested, including brain, and was the most abundant KIF m essage expressed in both retina and RPE, it was examined in more detai l and the complete similar to 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 b e a novel member of this family. Antibodies raised against a unique pe ptide specific to FKIF2 recognize an similar to 80 kd protein in homog enates 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. (C) 1997 Academic Press Limited.