Membrane-bound transcription factor site-2 protease, also known as S2P endopeptidase or site-2 protease (S2P), is an enzyme (EC 3.4.24.85) encoded by the MBTPS2 gene which liberates the N-terminal fragment of sterol regulatory element-binding protein (SREBP) transcription factors from membranes.
[1][2] S2P cleaves the transmembrane domain of SREBP, making it a member of the class of intramembrane proteases.
[3] S2P catalyses the following chemical reaction This enzyme belongs to the peptidase family M50.
This protease functions in the signal protein activation involved in sterol control of transcription and the ER stress response.
Mutations in this gene have been associated with ichthyosis follicularis with atrichia and photophobia (IFAP syndrome); IFAP syndrome has been quantitatively linked to a reduction in cholesterol homeostasis and ER stress response.