However, based on multiple sequence
alignments which included several type I keratins from other
vertebrates, this cDNA sequence appeared to be incomplete at
its 5 end. We therefore performed a 5 GeneRace (Gene-
RacerTM Kit, Invitrogen, Karlsruhe, Germany) on total RNA
extracted from amixture of different shark tissues and obtained
four DNA fragments ranging from 180 bp to 465 bp in length.