SSR4 Gene: Signal Sequence Receptor Subunit 4 - Function, Mutations, and Disease Associations

The SSR4 gene encodes the delta subunit of the signal sequence receptor (SSR) complex, also known as the translocon-associated protein (TRAP) complex. This complex is a component of the translocon machinery in the endoplasmic reticulum (ER) membrane, facilitating the translocation of nascent polypeptides across the ER membrane. SSR4 is essential for proper protein translocation and glycosylation. Mutations in SSR4 cause congenital disorder of glycosylation type 2Y (CDG2Y), an autosomal recessive disorder characterized by neurological impairment, developmental delay, and dysmorphic features.

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• R-HSA-1799339 - SRP-dependent cotranslational protein targeting to membrane

• R-HSA-392499 - Metabolism of proteins

• R-HSA-446203 - Asparagine N-linked glycosylation

• R-HSA-948021 - Translocation of proteins into the endoplasmic reticulum

SSR4 (Signal Sequence Receptor Subunit 4) is a 173-amino acid protein with a molecular weight of approximately 19 kDa. It is an integral membrane protein localized to the endoplasmic reticulum (ER) membrane. As part of the TRAP complex (comprising SSR1, SSR2, SSR3, and SSR4), it binds signal sequences of nascent polypeptides and facilitates their translocation into the ER lumen. The protein is essential for proper N-glycosylation and protein folding. Defects in SSR4 lead to congenital disorder of glycosylation type 2Y (CDG2Y), characterized by neurological and developmental abnormalities.