Sterol-sensing domain
IPR000731
Definition
The sterol-sensing domain (SSD) is an around 180 residues long cluster of five membrane-spanning segments. The SSD domain is conserved across phyla and confers sensitivity to regulation by sterol. It 'senses' the presence of sterol substrates through interactions and may modulate protein behaviours with changing sterol levels. SSD is present in several membrane proteins that function in cholesterol metabolism, transport, and signalling. This domain is build around a conserved core that is essential for the sterol-dependent functions. Conformational changes of SSD are crucial for the sterol sensing and transport PMID:29954986. Based on their functions and structures, SSD-containing proteins were categorised into two types - moderator (M) class and transporter (T) class PMID:35012873. Members in class M are Scap and HMGCR, both of which moderate the rate of sterol synthesis based on current sterol levels. Class T transporters, including NPC1, Ptch, and their homologs share a nearly identical transmembrane (TM) core with the bacterial multidrug-resistance transporters in the resistance/nodulation/division (RND) family. In class T, the conserved TM core consists of 12 TMs that fold into two repeats, named SSD and SSDL (SSD-like). In addition to the proteins above, the SSD is also found in a number of bacterial drug resistance proteins.
13 human proteins with this domain
Each is a reviewed human protein in the Seroatlas serome and a potential autoantibody target; this domain groups them into one antibody-relevant category. Every entry links to its own record.
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