PLATELETS AND THROMBOPOIESIS The VPS33B-binding protein VPS16B is required in megakaryocyte and platelet

Patients with platelet or dense -granule defects have bleeding problems. Although several proteins are known to be required for -granule development, less is known about -granule biogenesis. Our previ-ous work showed that the BEACH protein NBEAL2 and the Sec1/Munc18 protein VPS33B are required for-granule biogen-esis. Using a yeast two-hybrid screen, mass spectrometry, coimmunoprecipita-tion, and bioinformatics studies, we iden-tified VPS16B as a VPS33B-binding pro-tein. Immunoblotting confirmed VPS16B expression in various human tissues and cells including megakaryocytes and plate