The role of BiP in endoplasmic reticulum-associated degradation of major histocompatibility complex class I heavy chain induced by cytomegalovirus proteins.

Human cytomegalovirus (HCMV1) US11 and US2 proteins cause rapid degradation of major histocompatibility complex (MHC) molecules, apparently by ligating cellular endoplasmic reticulum (ER)-associated degradation machinery. Here, we show that US11 and US2 bind the ER chaperone BiP. Four related HCMV proteins, US3, US7, US9, and US10, which do not promote degradation of MHC proteins, did not bind BiP.

Receptor binding specificities of Herstatin and its intron 8-encoded domain.

Retention of intron 8 in alternative HER-2 mRNA generates an inhibitory secreted ligand, Herstatin, with a novel receptor-binding domain (RBD) encoded by the intron. This study examines binding interactions with several receptors and investigates sequence variations in intron 8. The RBD, expressed as a peptide, binds at nM concentrations to HER-2, the EGFR, DeltaEGFR, HER-4 and to the IGF-1 receptor, but not to HER-3 nor to the FGF-3 receptor, whereas a rare mutation in the RBD (Arg to Ile) eliminates receptor binding.