Transmembrane 4 L6 family member 20 (Tm4sf20)

Polytopic transmembrane protein. Inhibits regulated intramembrane proteolysis (RIP) of CREB3L1, inhibiting its activation and the induction of collagen synthesis.

In response to ceramide, which changes TM4SF20 membrane topology, stimulates RIP activation of CREB3L1. Ceramide reverses the direction through which transmembrane helices are translocated into the endoplasmic reticulum membrane during translation of TM4SF20, this mechanism is called'regulated alternative translocation' (RAT) and modulates the operation of the transmembrane protein.