Membrane-bound transcription factor site-1 protease

Membrane-bound transcription factor site-1 protease, or site-1 protease (S1P) for short, also known as subtilisin/kexin-isozyme 1 (SKI-1), is an is_associated_with::enzyme (EC 3.4.21.112) that in humans is encoded by the MBTPS1 is_associated_with::gene. S1P cleaves the is_associated_with::endoplasmic reticulum loop of is_associated_with::sterol regulatory element-binding protein (SREBP) is_associated_with::transcription factors.

Function
This gene encodes a member of the is_associated_with::subtilisin-like proprotein convertase family, which includes proteases that process protein and peptide precursors trafficking through regulated or constitutive branches of the secretory pathway. The encoded protein undergoes an initial autocatalytic processing event in the is_associated_with::endoplasmic reticulum (ER) to generate a is_associated_with::heterodimer which exits the ER and sorts to the cis/medial-Golgi where a second autocatalytic event takes place and the catalytic activity is acquired. It encodes a type 1 membrane bound protease which is ubiquitously expressed and regulates cholesterol or lipid homeostasis via cleavage of substrates at non-basic residues.

Clinical significance
Mutations in this gene may be associated with lysosomal dysfunction.