Molecular properties of cardiac tail-anchored membrane protein SLMAP are consistent with structural role in arrangement of excitation-contraction coupling apparatus.
The spatial arrangement of the cell-surface membranes (sarcolemma and transverse tubules) and internal membranes of the sarcoplasmic reticulum relative to the myofibril is critical for effective excitation-contraction (E-C) coupling in cardiac myocytes; however, the molecular determinants of this order remain to be defined. Here, we ascribe molecular and cellular properties to the coiled-coil, tail-anchored sarcolemmal membrane-associated protein (SLMAP) that are consistent with a potential role in organizing the E-C coupling apparatus of the cardiomyocyte. The expression of SLMAP was developmentally regulated and its localization was distinctly apparent at the level of the membranes involved in regulating the E-C coupling mechanism. Several SLMAP isoforms were expressed in the cardiac myocyte with unique COOH-terminal membrane anchors that could target this molecule to distinct subcellular membranes. Protein interaction analysis indicated that SLMAPs could self assemble and bind myosin in cardiac muscle. The cardiac-specific expression of SLMAP isoforms that can be targeted to distinct subcellular membranes, self assemble, and interact with the myofibril suggests a potential role for this molecule in the structural arrangement of the E-C coupling apparatus.
Guzzo
Rosa M
RM
Dept. of Cellular and Molecular Medicine, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5.
Salih
Maysoon
M
Moore
Edwin D
ED
Tuana
Balwant S
BS
D000367:Age Factors; D000818:Animals; D019556:COS Cells; D002522:Chlorocebus aethiops; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006321:Heart / Q000254:growth & development / Q000502:physiology; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D051379:Mice; D009200:Myocardial Contraction / Q000502:physiology*; D032383:Myocytes, Cardiac / Q000502:physiology*; D011247:Pregnancy; D017434:Protein Structure, Tertiary; D012508:Sarcolemma / Q000502:physiology; D012519:Sarcoplasmic Reticulum / Q000502:physiology*; D013329:Structure-Activity Relationship; D014162:Transfection
D008565:Membrane Proteins; C493783:Slmap protein, mouse