Modelling of a voltage-dependent Ca2+ channel B subunit as a basis for understanding its functional properties

Structure prediction methods have been used to establish a domain structure for the voltage-dependent calcium channel beta subunit, beta 1b. One domai n was identified from homology searches as an SH3 domain, whilst another ma s shown, using threading algorithms, to be similar to yeast guanylate kinas e. This domain structure suggested relatedness to the membrane-associated g uanylate kinase protein family, and that the N-terminal domain of the beta subunit might be similar to a PDZ domain. Three-dimensional model structure s have been constructed for these three domains. The extents of the domains are consistent with functional properties and mutational assays of the sub unit, and provide a basis for understanding its modulatory function. (C) 19 99 Federation of European Biochemical Societies.