Two populations of beta-spectrin in rat skeletal muscle.
We use immunoblotting, immunoprecipitation, and centrifugation in sucrose density gradients to show that the product of the erythrocyte beta-spectrin gene in rat skeletal muscle (muscle beta-spectrin) is present in two states, one associated with fodrin, and another that is not associated with any identifiable spectrin or fodrin subunit. Immunofluorescence studies indicate that a significant amount of beta-spectrin without alpha-fodrin is present in the myoplasm of some muscle fibers, and, more strikingly, at distinct regions of the sarcolemma. These results suggest that alpha-fodrin and muscle beta-spectrin associate in muscle in situ, but that some muscle beta-spectrin without a paired alpha-subunit forms distinct domains at the sarcolemma.
Porter
G A
GA
Department of Physiology, University of Maryland School of Medicine, Baltimore, USA.
Scher
M G
MG
Resneck
W G
WG
Porter
N C
NC
Fowler
V M
VM
Bloch
R J
RJ
D000818:Animals; D002352:Carrier Proteins / Q000032:analysis*; D002499:Centrifugation, Density Gradient; D005260:Female; D005455:Fluorescent Antibody Technique; D015151:Immunoblotting; D008840:Microfilament Proteins / Q000032:analysis*; D018485:Muscle Fibers, Skeletal / Q000737:chemistry; D009124:Muscle Proteins / Q000032:analysis*; D018482:Muscle, Skeletal / Q000737:chemistry*; D010446:Peptide Fragments / Q000032:analysis; D011233:Precipitin Tests; D017434:Protein Structure, Tertiary; D051381:Rats; D012508:Sarcolemma / Q000737:chemistry; D013049:Spectrin / Q000032:analysis*
D002352:Carrier Proteins; D008840:Microfilament Proteins; D009124:Muscle Proteins; D010446:Peptide Fragments; D013049:Spectrin