(I) The relative binding affinity of FLAG-tagged full-length and truncated SCAP proteins with endogenous TMEM33 and RNF5. The band intensity of TMEM33 and RNF5 in Appendix Fig S2D were quantified and normalized with the FLAG control. SCAP protein encompasses eight transmembrane (TM) helices in N-terminus (TM 2-6: sterol-sensing domain) and a WD40 domain in C-terminus with total of 1279 aa. 