TRAPPC2 (Trafficking Protein Particle Complex Subunit 2), also known as sedlin, MIP-2A, SEDL, or SEDT, is a protein that in humans is encoded by the TRAPPC2 gene located on the X-chromosome at position Xp22.2.
Function
The TRAPPC2 gene provides instructions for producing the protein sedlin, which is a component of the trafficking protein particle (TRAPP) complex. This multisubunit complex is involved in the targeting and fusion of endoplasmic reticulum (ER)-to-Golgi transport vesicles with their acceptor compartment. Sedlin is required for transporting large proteins, including procollagens, from the endoplasmic reticulum to the Golgi apparatus. The protein can also bind MBP1 (alpha-enolase) and block its transcriptional repression capability.
Gene Structure
The TRAPPC2 gene is located between base pairs 13,712,241 and 13,734,634 on the X chromosome. A processed pseudogene of this gene is located on chromosome 19, with additional pseudogenes found on chromosome 8 and the Y chromosome. Two transcript variants encoding the same protein have been identified.
Clinical Significance
Mutations in the TRAPPC2 gene cause X-linked spondyloepiphyseal dysplasia tarda (SEDT), a condition that impairs bone growth and occurs almost exclusively in males, typically appearing between ages 6 and 10. More than 50 mutations in the gene have been identified, with nearly all resulting in a nonfunctional sedlin protein. This disrupts procollagen transport from the endoplasmic reticulum, reducing mature collagen production and impairing the development of bones, cartilage, and other connective tissues.
Protein Interactions
TRAPPC2 has been shown to interact with alpha-enolase (MBP1) and chloride intracellular channel protein 1 (CLIC1).
