This transmembrane domain is found in metal transporter proteins such as cyclin M 1/2 (CNNM). CNNMs are integral membrane proteins that are conserved from bacteria to humans. CNNM family members influence metal ion homeostasis through mechanisms that ...
This transmembrane domain is found in metal transporter proteins such as cyclin M 1/2 (CNNM). CNNMs are integral membrane proteins that are conserved from bacteria to humans. CNNM family members influence metal ion homeostasis through mechanisms that may not involve direct membrane transport of the ions. Structurally, CNNMs are complex proteins that contain an extracellular N-terminal domain preceding a transmembrane domain, a 'Bateman module', which consists of two cystathionine- beta-synthase (CBS) domains Pfam:PF00571, and a C-terminal cNMP (cyclic nucleotide monophosphate) binding domain [1, 2, 3, 4]. This entry describes the CNNM transmembrane domain which contains four hydrophobic regions and forms a dimer through hydrophobic contacts between TM2 and TM3, in which each chain is composed of three transmembrane helices (TM1-3), a pair of short helices exposed on the intracellular side, and a juxtamembrane (JM) helix that forms a belt-like structure [2,5]. The homodimer adopts an inward-facing conformation with a negatively charged cavity containing a conserved pi-helical turn in TM3 that coordinates a Mg2 ion [5].
