Problem: Summarized in medical terms Based on sequence and topological differences,6 mammalian TRPs can be categorized into the following seven subfamilies: group 1 with five subfamily members (TRPC, TRPV, TRPM, TRPN, and TRPA), and group 2 with two subfamilies (TRPP and TRPML) (Table 1 and Fig. 2).17 An additional subfamily, TRPY, consists of yeast TRPs, which are distantly related to group 1 and group 2 TRPs.18 The first and second groups both have six transmembrane structural domains and are permeable to cations. TRPA, TRPV, and TRPC channels contain ankyrin repeat sequences in their intracellular N-terminal structural domains, whereas TRPC and TRPM subfamilies possess a proline-rich "TRP structural domain" in the C-terminal region near the presumed transmembrane segment.19 Group 2 channels also have high sequence homology in their transmembrane structural domains and are only distally related to the genes of group 1 channels because they contain a large lumenal/extracellular domain between transmembrane helix 1 (S1) and S2.20. Need Assignment Help?