Points of convergence between Ca2+ and Ras signalling pathways

p21 Ras proteins play a critical role in the regulation of cellular growth and differentiation. In addition, Ras and proteins which regulate Pas activ ity have been implicated in long-term memory consolidation and long-term po tentiation processes. Over the last few years, much evidence has emerged wh ich indicates that changes in cytoplasmic Ca2+ levels can regulate Ras prot ein activity and subsequent biological function. Also, Ras proteins themsel ves can modulate intracellular Ca2+ levels by regulating both Ca2+ release and Ca2+ influx processes. Here we examine the signalling components which regulate Pas activity and, in particular, consider points of convergence be tween intracellular Ca2+ and p21 Ras signalling processes. In addition, we consider the possible biological consequences resulting from the integratio n of these signalling pathways and highlight the importance of our understa nding protein-protein interactions. Finally, we discuss the possibility of protein-protein interactions mediated via Ca2+-responsive structural domain s, such as the C2 and IQ domains, playing important roles in Ca2+-dependent Ras functions yet to be established. (C) 1998 Elsevier Science B.V. All ri ghts reserved.