Part of the Sec61 complex, which is the major component of channel-forming translocon complex that mediates protein translocation across the endoplasmic reticulum (ER). The functional states of the translocon complex include co- and post-translational ER import, cotranslational membrane protein integration and retrograde transport of misfolded proteins out of the ER. In the cotranslational pathway, ribosomes synthesizing presecretory proteins are targeted to the translocon by the cytosolic signal recognition particle (SRP) and its ER-localized receptor. The association of the Sec61 complex with the ribosome is mediated by the 28S rRNA of the large ribosomal subunit. SRP-independent post-translational translocation requires the association of additional factors, such as the Sec62/63 complex and KAR2. Also part of the Ssh1 complex, which probably is the major component of a channel-forming translocon complex that may function exclusively in the cotranslational pathway of protein ER import. Component of the heterotrimeric Sec61 complex, which is composed of SSH1, SBH1 and SSS1. Presumably three to four Sec61 heterotrimers assemble into an oligomeric ring with a central aqueous pore. In cotranslational ER import, the pore diameter varies from 9-15 A in a ribosome-free resting state to 40-60 A in a functional state when associated with the ribosome. The Sec61 complex is part of a channel-forming translocon complex whose composition seem to change dependent upon different functional states. During post-translational ER import the Sec61 complex associates with the Sec62/63 complex to form the Sec complex. SSH1 is a component of the heterotrimeric Ssh1 complex, which is composed of SSH1, SBH2 and SSS1. SSS1 interacts with OST1, OST4, SWP1 and WBP1, components of the OT complex. Belongs to the SecE/SEC61-gamma family.