Fig. 1. Structure and distributions of kinectin isoforms. (A) Schematic diagram depicting the structure of mouse kinectin cDNA. Grey triangles represent the five insertion sequences (variable domains or `inserts' V1-V5) that are used combinatorially to generate splice variants with alternative C-termini. The five inserts are 69, 87, 72, 84 and 110 bp in size, maintaining the correct ORF. V5 includes a stop codon and generates a C-terminus similar to that described in human and chicken whereas lack of V5 creates a novel, 11 a.a. C-terminus extending past the insertion site. The positions of oligonucleotide pair V₀up/V₀do, used to co-amplify putative kinectin isoforms from mouse hippocampal tissue of distinct developmental stages and primary mouse astrocyte cultures, is indicated with arrows. (B) RT-PCR co-amplification of kinectin isoforms from E15 embryonic mouse hippocampus, using oligonucleotide pair V₀up/V₀do. At least five differently sized products are detectable on the gel (arrowheads). The mixed product was subcloned and a large number of clones subsequently analysed (see text). (C) Agarose electrophoresis of PCRs, using oligonucleotide pair V₀up/V₀do with cDNAs cloned in plasmid pCR2.1. Distinct sets of kinectin isoforms derived from mouse E15 and adult hippocampus and astrocytic cultures, respectively are shown.