Ca2(+)-dependent mobility shift of parvalbumin in one- and two-dimensional gel-electrophoresis

Under Ca2(+)-loaded conditions parvalbumin migrates in one- and two-dimensional gel-systems as a double-band or -spot whereas in Ca2(+)-free condition it appears as one band or spot. Parvalbumin (PV), a member of the family of calcium-binding proteins [1], was first described in 1934 [2] and occurs in fast-contracting muscles and in subpopulations of neurons in vertebrates and humans [3,4,5]. The physical characteristics of molecular weight (Mv 12 KD), isoelectric point (pI 4.9) and Ca2(+)-binding properties are established (PV binds 2 Ca2+ per molecule) [5,6]. Physiological roles discussed for PV range from trigger- to buffer-protein of intracellular Ca2(+)-ions [7]. In this paper we report an as yet not described mobility shift of PV in gel-electrophoresis after manipulation of the Ca2+ concentration, which may have implications for its physiological function.