Immunolocalization of AMP-deaminase isozymes in human skeletal muscle and cultured muscle cells: concentration of isoform M at the neuromuscular junction.
The three major isoforms of AMP-deaminase (AMPda) were localized in human skeletal muscle and cultured muscle cells by immunocytochemistry. The M isoform was mainly located in Type II muscle fibers and showed a clear cross-striation. Particularly strong staining was present at the neuromuscular junction. Capillaries were also immunoreactive. The L isoform was predominantly observed in nerve bundles and to a minor extent in smooth muscle cells and endothelial cells. The E isoform was predominantly present in smooth muscle cells, and to a lesser extent in Type I muscle fibers and nerve bundles. In quadriceps muscle of patients with myoadenylate deaminase deficiency, no immunostaining for the M isozyme was observed, whereas reactivity for the L and E isoforms was unaltered. In human muscle cell cultures, mononuclear cells, including myoblasts, were immunoreactive for the L isoform and to a lesser extent the E isoform, whereas the M isoform was absent. In myotubes, diffuse or fibrillar staining was present for all three isoforms, but only the M isoform showed a clear cross-striation pattern in highly differentiated myotubes.
Department of Biochemistry, University of Nijmegen, The Netherlands.
T H
TH
van Kuppevelt
J H
JH
Veerkamp
W N
WN
Fishbein
N
N
Ogasawara
R L
RL
Sabina
D000659:AMP Deaminase / Q000032:analysis* / Q000172:deficiency; D000293:Adolescent; D002478:Cells, Cultured; D002648:Child; D005455:Fluorescent Antibody Technique; D006801:Humans; D007527:Isoenzymes / Q000032:analysis*; D009132:Muscles / Q000201:enzymology*; D009469:Neuromuscular Junction / Q000201:enzymology*
D007527:Isoenzymes; D000659:AMP Deaminase