The protein encoded by this gene belongs to the SECY/SEC61- alpha family. It appears to play a crucial role in the insertion of secretory and membrane polypeptides into the endoplasmic reticulum. This protein found to be tightly associated with membrane-bound ribosomes, either directly or through adaptor proteins. This gene encodes an alpha subunit of the heteromeric SEC61 complex, which also contains beta and gamma subunits. [provided by RefSeq, Jul 2008].