A novel protein found in the I bands of myofibrils is produced by alternative splicing of the DLST gene.
BACKGROUND
It is not known if the dihydrolipoamide succinyltransferase (DLST) gene, a mitochondrial protein, undergoes alternative splicing. We identified an uncharacterized protein reacting with an anti-DLST antibody in the I bands of myofibrils in rat skeletal muscle.


METHODS
Immunocytochemical staining with an anti-DLST antibody, the purification and amino acid sequence analysis of the protein, and the isolation and sequencing of the protein's cDNA were carried out to clarify the properties of the protein and its relationship to the DLST gene.


RESULTS
A pyrophosphate concentration >10 mM was necessary to extract the protein from myofibrils in the presence of salt with a higher concentration than 0.6 M, at an alkaline pH of 7.5-8.0. The protein corresponded to the amino acid sequence of the C-terminal side of DLST. The cDNAs for this protein were splicing variants of the DLST gene, with deletions of both exons 2 and 3, or only exon 2 or 3. These variants possessed an open reading frame from an initiation codon in exon 8 of the DLST gene to a termination codon in exon 15, generating a protein with a molecular weight of 30 kDa.


CONCLUSIONS
The DLST gene undergoes alternative splicing, generating the protein isolated from the I bands of myofibrils.


CONCLUSIONS
The DLST gene produces two different proteins with quite different functions via alternative splicing.
Matuda
Sadayuki
S
Department of Biology and Health Science, Kanoya National Institute of Fitness and Sports, Kanoya, Kagoshima 891-2393, Japan.
Arimura
Takuro
T
Kimura
Akinori
A
Takekura
Hiroaki
H
Ohta
Shigeo
S
Nakano
Kyoko
K
D000217:Acyltransferases / Q000235:genetics* / Q000378:metabolism; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D007150:Immunohistochemistry; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000201:enzymology / Q000378:metabolism; D009210:Myofibrils / Q000201:enzymology / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012518:Sarcomeres / Q000201:enzymology / Q000378:metabolism*; D017422:Sequence Analysis, DNA
D018076:DNA, Complementary; D007527:Isoenzymes; D012333:RNA, Messenger; D000217:Acyltransferases; C021515:dihydrolipoamide succinyltransferase