title: Costameres: repeating structures at the sarcolemma of skeletal muscle.
abstract: Costameres, structures at the plasma membrane of skeletal muscle, are present in a rectilinear array that parallels the organization of the underlying contractile apparatus. Costameres have three major functions: to keep the plasma membrane, or sarcolemma, aligned and in register with nearby contractile structures; to protect the sarcolemma against contraction-induced damage; and to transmit some of the forces of contraction laterally, to the extracellular matrix. These functions require that costameres link the contractile apparatus through the membrane to the extracellular matrix. Mutations to key components of costameres cause these structures to lose their rectilinear organization and can result in muscle weakness or death. This article summarizes the evidence that costameres are composed of large complexes of integral and peripheral membrane proteins that are linked to the contractile apparatus by intermediate filaments and to the extracellular matrix by laminin. They also present evidence that costameres are altered when key costameric components are missing, as in a murine form of muscular dystrophy.
authors.affiliation: Departments of Physiology, University of Maryland School of Medicine, 655 W. Baltimore Street, Baltimore, MD 21201, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Bloch
authors.forename: Yassemi
authors.initials: Y
authors.lastname: Capetanaki
authors.forename: Andrea
authors.initials: A
authors.lastname: O'Neill
authors.forename: Patrick
authors.initials: P
authors.lastname: Reed
authors.forename: McRae W
authors.initials: MW
authors.lastname: Williams
authors.forename: Wendy G
authors.initials: WG
authors.lastname: Resneck
authors.forename: Neil C
authors.initials: NC
authors.lastname: Porter
authors.forename: Jeanine A
authors.initials: JA
authors.lastname: Ursitti
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000648:ultrastructure*; D003599:Cytoskeleton / Q000378:metabolism / Q000502:physiology; D005109:Extracellular Matrix / Q000502:physiology; D006801:Humans; D007150:Immunohistochemistry; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000502:physiology* / Q000648:ultrastructure*; D009136:Muscular Dystrophies / Q000473:pathology / Q000503:physiopathology; D012508:Sarcolemma / Q000378:metabolism / Q000502:physiology*