S. Matuda et al., A POLYPEPTIDE DERIVED FROM MITOCHONDRIAL DIHYDROLIPOAMIDE SUCCINYLTRANSFERASE IS LOCATED ON THE PLASMA-MEMBRANE IN SKELETAL-MUSCLE, Biochemical and biophysical research communications, 241(1), 1997, pp. 151-156
Dihydrolipoamide succinyltransferase (DLST) is the core-enzyme of 2-ox
oglutarate dehydrogenase complex which is located in mitochondria. In
this study, several tissues from rat and human were immunostained with
an affinity-purified anti-DLST antibody. Of the tissues examined, the
plasma membrane of skeletal muscle was immunostained with the antibod
y besides mitochondria. Furthermore, subcellular fractionation analysi
s coupled with Western blotting demonstrated that the antigen of the a
nti-DLST antibody is distributed on the plasma membrane fraction in ad
dition to the mitochondria fraction in skeletal muscle and that it is
free from the complex. The molecular weight of the polypepetide bound
to the plasma membrane was about 20 kilodaltons (kDa). The polypeptide
was purified by immunoprecipitation and its N-terminal amino-acid seq
uence was determined. The aminoacid sequence exactly corresponded to a
part of DLST. Northern blots revealed the presence of mRNA correspond
ing to the 20 kDa protein. We are the first to report that a mitochond
rial protein is also present on the plasma membrane in skeletal muscle
as well as in mitochondria. (C) 1997 Academic Press.