USE OF METHIONINE-SE-75 AS A TRACER OF THROMBOCYTOPOIESIS .1. INVIVO INCORPORATION OF THE TRACER INTO PLATELET PROTEINS - BIOCHEMICAL-STUDY

This study was undertaken to define to which platelet components 75Se-methionine is bound after its injection to normal rats, and to study the curves of specific radioactivity of each labelled fraction. It has been shown that, for a part, platelet labelling is due to adsorption of plasma proteins (albumin and fibrinogen) after their synthesis. For another part, methionine is directly incorporated in the bone marrow precursors into platelet actomyosin, a protein constituent of the cells; the variations of the specific radioactivity of this component indicate that 75Se-methionine can be used as a cohort label of platelets.