ISSN:
1432-1432
Keywords:
Key words: Troponin — Muscle contraction — Cell motility — Calcium signal transduction — E-C coupling
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract. Ca2+-regulated motility is essential to numerous cellular functions, including muscle contraction. Systems with troponin C, myosin light chain, or calmodulin as the Ca2+ receptor have evolved in striated muscle and other types of cells to transduce the cytoplasm Ca2+ signals into allosteric conformational changes of contractile proteins. While these Ca2+ receptors are homologous proteins, their coupling to the responding elements is quite different in various cell types. The Ca2+ regulatory system in vertebrate striated muscle represents a highly specialized such signal transduction pathway consisting of the troponin complex and tropomyosin associated with the actin filament. To understand the molecular mechanism in the Ca2+ regulation of muscle contraction and cell motility, we have revealed a preserved ancestral close linkage between the genes encoding two of the troponin subunits, troponin I and troponin T, in the genome of mouse. The data suggest that the troponin I and troponin T genes may have originated from a single locus and evolved in parallel to encode a striated muscle-specific adapter to couple the Ca2+ receptor, troponin C, to the actin–myosin contractile machinery. This hypothesis views the three troponin subunits as two structure–function domains: the Ca2+ receptor and the signal transducing adapter. This model may help to further our understanding of the Ca2+ regulation of muscle contraction and the structure–function relationship of other potential adapter proteins which are converged to constitute the Ca2+ signal transduction pathways governing nonmuscle cell motility.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/PL00006600
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