Sterol regulatory element-binding protein cleavage-activating protein

UniProtKB accession:  O43043

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UniProtKB description:  Escort protein required for sre1 processing at low sterol as well as oxygen levels. May regulate export of the scp1/sre1 complex from the ER at low sterol or oxygen levels (PubMed:15797383, PubMed:17595166). 4-methyl sterols bound to scp1 may mask an ER export signal in scp1 leading to retention of the complex in the ER (PubMed:15797383, PubMed:17595166). Release of 4-methyl sterols may trigger a conformational change in the SSD domain of scp1 unmasking the ER export signal leading to recruitment into COPII-coated vesicles, transport to the Golgi complex, proteolytic cleavage of sre1 in the Golgi, release of the transcription factor fragment of sre1 from the membrane, its import into the nucleus and up-regulation of genes required for ergosterol biosynthesis as well as anaerobic growth (By similarity). Binds 4-methyl sterols (PubMed:17595166).