The physiologically regulated alternative splicing patterns of fast
troponin t rna are conserved in mammals.
Briggs, Margaret M., Fred Schachat.
Department of Cell Biology, Duke University Medical Center, Durham,
North Carolina 27710 USA
APStracts 2:0266C, 1995.
N-terminal isoforms of fast troponin T (TnT) are generated by
alternative splicing of fast TnT RNA transcripts. Significantly
different estimates for the number of isoforms have been obtained by
nucleic acid and protein chemical studies. To resolve this
controversy and determine whether specific 5'-splicing patterns
correlate with fiber phenotype, we generated representative
populations of 5'-TnT cDNAs from the TnT mRNAs expressed in a set of
physiologically and anatomically diverse skeletal muscles. Sequencing
and restriction enzyme analyses revealed a total of nine cDNAs that
encode the 6 adult and 3 perinatal N-terminal TnT variants previously
identified. Three major 5'-splicing pathways (the TnT1f, TnT2f, and
TnT3f patterns) account for more than 90% of the TnT mRNAs and
proteins in adult rabbit skeletal muscle. Comparative studies in rat,
mouse, and human show that these splicing patterns are conserved and
that fast fibers that are primarily glycolytic utilize the TnT1f and
TnT2f patterns preferentially, while fast fibers that are primarily
oxidative use the TnT1f and 3f patterns preferentially.
Received 21 March 1995; accepted in final form 27 June 1995.
APS Manuscript Number C159-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 18 July 1995.