Protein transport protein Sec31A is a protein that in humans is encoded by the SEC31A gene.

The protein encoded by this gene is similar to yeast Sec31 protein. Yeast Sec31 protein is known to be a component of the COPII protein complex which is responsible for vesicle budding from endoplasmic reticulum (ER). This protein was found to colocalize with SEC13, one of the other components of COPII , in the subcellular structures corresponding to the vesicle transport function. An immunodepletion experiment confirmed that this protein is required for ER-Golgi transport. Alternative splicing results in multiple transcript variants encoding different isoforms.
Function: Component of the coat protein complex II (COPII) which promotes the formation of transport vesicles from the endoplasmic reticulum (ER). The coat has two main functions, the physical deformation of the endoplasmic reticulum membrane into vesicles and the selection of cargo molecules (By similarity).