title: Evolution of skeletal type e-c coupling: a novel means of controlling calcium delivery.
abstract: The functional separation between skeletal and cardiac muscles, which occurs at the threshold between vertebrates and invertebrates, involves the evolution of separate contractile and control proteins for the two types of striated muscles, as well as separate mechanisms of contractile activation. The functional link between electrical excitation of the surface membrane and activation of the contractile material (known as excitation-contraction [e-c] coupling) requires the interaction between a voltage sensor in the surface membrane, the dihydropyridine receptor (DHPR), and a calcium release channel in the sarcoplasmic reticulum, the ryanodine receptor (RyR). Skeletal and cardiac muscles have different isoforms of the two proteins and present two structurally and functionally distinct modes of interaction. We use structural clues to trace the evolution of the dichotomy from a single, generic type of e-c coupling to a diversified system involving a novel mechanism for skeletal muscle activation. Our results show that a significant structural transition marks the protochordate to the Craniate evolutionary step, with the appearance of skeletal muscle-specific RyR and DHPR isoforms.
authors.affiliation: Department of Cell and Developmental Biology, University of Pennsylvania, Philadelphia, PA 19104. Valentina.Di-Biase@uibk.ac.at
authors.forename: Valentina
authors.initials: V
authors.lastname: Di Biase
authors.forename: Clara
authors.initials: C
authors.lastname: Franzini-Armstrong
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001692:Biological Transport; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D043344:Chordata; D019143:Evolution, Molecular; D005614:Freeze Fracturing; D006196:Hagfishes; D007798:Lampreys; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000378:metabolism*; D009206:Myocardium / Q000378:metabolism; D010802:Phylogeny; D020033:Protein Isoforms; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D013045:Species Specificity
chemical_list: D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D020033:Protein Isoforms; D019837:Ryanodine Receptor Calcium Release Channel; D002118:Calcium