Protein transport protein Sec61 subunit alpha isoform 1 is a protein in humans that is encoded by SEC61A1 gene. Plays a crucial role in the insertion of secretory and membrane polypeptides into the ER. Required for assembly of membrane and secretory proteins. Tightly associated with membrane-bound ribosomes, either directly or through adapter proteins. Plays a role in pronephric kidney tubule development (By similarity).