Identification and Characterization of the Interaction between VPS33B and SNAREs

• Main Author: Puhacz, Michael
• Other Authors: Kahr, Walter
• Language: en_ca
• Published: 2011
• Subjects: SNAREs; Sec1/Munc18; VPS33B; syntaxin-6; megakaryocyte; platelet; 0379
• Online Access: http://hdl.handle.net/1807/31394

VPS33B is a Sec1/Munc18 protein required for the biogenesis of α-granules in megakaryocytes, which give rise to platelets. Mutations in VPS33B cause arthrogryposis, renal dysfunction and cholestasis (ARC) syndrome. Platelets from ARC patients completely lack α-granules, causing a bleeding disorder. VPS33B plays a role in vesicular fusion events through its interaction with the SNARE proteins, though no such interactions have been identified. Here, it is shown that VPS33B interacts with STX6, a member of the syntaxin subfamily of SNAREs. The introduction of ARC mutations into VPS33B completely abrogated binding to STX6. Confocal microscopy studies revealed STX6 co-localizes well with markers of the α-granule biogenesis pathway. This implies a role for the interaction of VPS33B with STX6 in α-granule biogenesis. Based on the known structure of STX6 and that predicted of VPS33B, suggests a novel and unique mode of binding between VPS33B and STX6 compared to other identified SM-STX pairs.