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.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/31394 |
| Date | 19 December 2011 |
| Creators | Puhacz, Michael |
| Contributors | Kahr, Walter |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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