{Soft hyphen}{Soft hyphen}Reorientation of the first signal-anchor sequence during potassium channel biogene{Soft hyphen}{Soft hyphen}sis at the Sec61 complex

The majority of the polytopic proteins that are synthesised at the endoplasmic reticulum are integrated co-translationally via the Sec61 translocon, which provides lateral access for their hydrophobic transmembrane regions (TMs) to the phospholipid bilayer. A prolonged association between TMs of the potassium channel subunit, TASK-1, and the Sec61 complex suggests that the ER translocon coordinates the folding/assembly of the TMs present in the nascent chain. The N-terminus of both TASK-1 and Kcv, another potassium channel subunit of viral origin, has access to the N-glycosylation machinery located in the ER lumen, indicating that the Sec61 complex can accommodate multiple arrangements/orientations of TMs within the nascent chain, both in vitro and in vivo. Hence, the ER translocon can provide the ribosome bound nascent chain with a dynamic environment in which it can explore a range of different conformations en route to its correct transmembrane topology and final native structure.
Source: BJ Cell - Category: Biochemistry Authors: Tags: BJ Cell Source Type: research