Glycoproteins of rat skeletal muscle sarcolemma: characterization by two-dimensional gel electrophoresis and effect of denervation.
Sarcolemmal membrane glycoproteins from rat mixed, fast, and slow muscles were characterized by concanavalin A (ConA) binding following two-dimensional polyacrylamide gel electrophoresis (PAGE). Analysis of electrophoretic profiles revealed that although sarcolemmal membranes prepared from these muscle types contained common glycoprotein species, each had a distinct glycoprotein pattern. In sarcolemma from mixed muscle, three major classes of ConA binding glycoproteins could be distinguished: (i) an acidic species of 110,000-120,000 Da, pI 5.0 to 5.3 (CG-1, ConA binding glycoproteins-1); (ii) a group of highly charged isomers, ranging from 75,000 to 80,000 Da pI 5.2 to 8.2 (CG-2); and (iii) a group of charged isomers of predominantly acidic nature of approximately 50,000 Da pI 5.2 to 5.8 (CG-3). ConA bound exclusively to CG-1 in sarcolemma from a fast muscle (extensor digitorum longus muscle, EDL). In soleus muscle sarcolemma (slow fiber type) both CG-1 and CG-3 were readily detected but CG-2 was markedly diminished. ConA binding to slow muscle sarcolemma revealed as well a glycoprotein species of 66,000-70,000 Da, pI 4.3-5.1 (CG-4), which was unique to this fiber type and as such may be a specific marker for slow fiber type. Denervation had no significant effect on the properties of ConA binding to mixed or slow muscle sarcolemma but dramatically altered the ConA binding to fast muscle sarcolemma, specifically increasing binding to CG-2. These findings demonstrate that denervation differentially affects the metabolism of ConA binding glycoproteins in these muscle types.
Iannello
R C
RC
Children's Medical Research Foundation, Camperdown, New South Wales, Australia.
Jeffrey
P L
PL
D000818:Animals; D015180:Electrophoresis, Gel, Two-Dimensional; D005260:Female; D006023:Glycoproteins / Q000378:metabolism*; D009121:Muscle Denervation; D009132:Muscles / Q000378:metabolism* / Q000648:ultrastructure; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D012508:Sarcolemma / Q000378:metabolism*
D006023:Glycoproteins