[Contractile proteins and blood platelets]

There is evidence to indicate that the morphology and function of a cell depend on the nature and location of intracellular polymeric cytoskeletal structures. In non muscle cells, the main polymeric cytoskeletal structures are in general terms those of the microtubules and microfilaments: actin and myosin. The regulation of platelet contractile protein function is highly complex and proceeds by many different mechanisms. This biochemical complexity is required because actin, myosin and associated proteins have essential and various functions in not one but several of the events following platelet stimulation. The aim of this review is triple. To analyse, according to recent data, the properties of the platelet contractile proteins actin and actin-binding proteins, and myosin. To try to understand their role in the different steps of platelet activation: shape change, secretion, contraction and aggregation. To define the role of calcium in the contractile protein regulation.