Selective degradation of T cell antigen receptor chains retained in a pre-Golgi compartment

Abstract

We have examined the fate of newly synthesized T cell antigen receptor (TCR) subunits in a T cell hybridoma deficient in expression of the clonotypic β chain. Synthesis and assembly of the remaining chains proceed normally but surface expression of TCR chains is undetectable in these cells. A variety of biochemical and morphological techniques has been used to show that the TCR chains in these cells fail to be transported to any Golgi cisternae. Instead, they are retained in a pre-Golgi compartment which is either part of or closely related to the endoplasmic reticulum. The CD3-δ chain is degraded by a non-lysosomal process that is inhibited at temperatures at or below 27°C. By contrast, the remaining chains (CD3-ε, CD3-γ, and ζ) are very stable over 7 h. We propose possible mechanisms that may explain the differential fate of TCR chains retained in a pre-Golgi compartment.