Limit of platelet life span (8–10 days) is determined by the activity of a putative" internal
clock" composed of Bcl-2 family proteins, whereas the role of other molecular players in this
process remains obscure. Here, we sought to establish a central role of proteasome in
platelet life span regulation. Administration of mice with inhibitors of proteasome peptidase
activity induced significant thrombocytopenia. This was associated with enhanced clearance
of biotin-labeled platelets from circulation and reduction in average platelet half-life from 66 …