Selective sorting of alpha-granule proteins.
One of the main functions of blood platelets is to secrete a variety of substances that can modify a developing thrombus, regulate the growth of the vasculature, promote wound repair, and contribute to cell-adhesive events. A majority of this vast array of secreted proteins are stored in alpha-granules. Until recently, it was assumed that platelets contained one homogeneous population of alpha-granules that undergo complete de-granulation during platelet activation. This review focuses on the mechanisms of alpha-granule biogenesis and secretion, with a particular emphasis on recent findings that clearly demonstrate that platelets contain distinct subpopulations of alpha-granules that undergo differential release during activation. We consider the implications of this new paradigm of platelet secretion, discuss mechanisms of alpha-granule biogenesis, and review the molecular basis of transport and delivery of alpha-granules to assembling platelets.
Italiano
J E
JE
Division of Translational Medicine, Brigham and Women's Hospital, Vascular Biology Program, Boston, MA 02115, USA. jitaliano@rics.bwh.harvard.edu
Battinelli
E M
EM
D001792:Blood Platelets / Q000378:metabolism*; D006801:Humans; D021381:Protein Transport; D022142:Secretory Vesicles / Q000378:metabolism*