Affordable Access

deepdyve-link
Publisher Website

Characterization of two tropomyosin isoforms from the fast skeletal muscle of bluefin tuna Thunnus thynnus orientalis

Authors
  • Ochiai, Yoshihiro
  • Ozawa, Hideo
  • Huang, Ming-Chih
  • Watabe, Shugo
Type
Published Article
Journal
Archives of Biochemistry and Biophysics
Publisher
Elsevier BV
Publication Date
Jan 01, 2010
Volume
502
Issue
2
Pages
96–103
Identifiers
DOI: 10.1016/j.abb.2010.07.015
Source
Elsevier
Keywords
License
Unknown

Abstract

Fast skeletal muscle tropomyosin (TM) of tunas is composed of nearly equimolar amount of two isoforms designated α-TM and β-TM expediently based on their migration behavior in SDS–PAGE, whereas corresponding TMs from the other fish species are homogenous (α-type). The presence of β-TM is thus specific to tunas so far. The amino acid sequence of β-TM from bluefin tuna Thunnus thynnus orientalis, which has not been revealed to date unlike α-TM, was successfully obtained in this study by cDNA cloning. The coding region of β-TM cDNA comprised of an open reading frame of 855 bp encoding 284 amino acid residues, like most of the TMs. Unexpectedly, the sequence of β-TM showed high similarity to those of other vertebrate α-type TMs including tuna α-TM. Phylogenetic analysis also showed that β-TM has the closest relationship with α-TM of tuna. This fact was quite unlike the relation of mammalian α- and β-TMs. Based on the distribution of amino acid substitutions, it was suggested that tuna TM isoforms are the products of different genes. By thermodynamic analysis of native and reconstituted TMs, it was demonstrated that β-TM is less thermostable than α-TM. Proteolytic digestion also supported the lower stability of the former.

Report this publication

Statistics

Seen <100 times