title: Two populations of beta-spectrin in rat skeletal muscle.
abstract: 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.
authors.affiliation: Department of Physiology, University of Maryland School of Medicine, Baltimore, USA.
authors.forename: G A
authors.initials: GA
authors.lastname: Porter
authors.forename: M G
authors.initials: MG
authors.lastname: Scher
authors.forename: W G
authors.initials: WG
authors.lastname: Resneck
authors.forename: N C
authors.initials: NC
authors.lastname: Porter
authors.forename: V M
authors.initials: VM
authors.lastname: Fowler
authors.forename: R J
authors.initials: RJ
authors.lastname: Bloch
mesh_terms: 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*
chemical_list: D002352:Carrier Proteins; D008840:Microfilament Proteins; D009124:Muscle Proteins; D010446:Peptide Fragments; D013049:Spectrin