Myosin heavy-chain mRNA is present in both myofibrillar and subsarcolemmal regions of muscle fibres.
Hybridization in situ with riboprobes to the myosin heavy-chain slow isoform showed that, in the rat soleus muscle, the myosin heavy-chain mRNA was distributed throughout the myofibres. There was greater density of autoradiographic grains in the subsarcolemmal regions of the fibres, but there was also a considerable number of grains in the core myofibrillar region of the fibres. Microdensitometry showed that the grain density in the myofibrillar region was approximately half that in the subsarcolemmal rim; this would correspond to some 70% of the mRNA being present in the myofibrillar region. The results are consistent with the hypothesis that myosin is synthesized on polyribosomes present in the intermyofibrillar cytoplasm.
Hesketh
J
J
Division of Biochemical Sciences, Rowett Research Institute, Aberdeen, Scotland, U.K.
Campbell
G
G
Loveridge
N
N
D000818:Animals; D001345:Autoradiography; D008297:Male; D009210:Myofibrils / Q000737:chemistry*; D009218:Myosins / Q000235:genetics*; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D012508:Sarcolemma / Q000737:chemistry*
D012333:RNA, Messenger; D009218:Myosins