harmonin-homology domain (harmonin_N_like domain) of malcavernin (CCM2)
CCM2 (also called malcavernin; C7orf22/chromosome 7 open reading frame 22; OSM) along with CCM1 and CCM3 constitutes a set of proteins which when mutated are responsible for cerebral cavernous malformations, an autosomal dominant neurovascular disease characterized by cerebral hemorrhages and vascular malformations in the central nervous system. CCM2 plays many functional roles. CCM2 functions as a scaffold involved in small GTPase Rac-dependent p38 mitogen-activated protein kinase (MAPK) activation when the cell is under hyperosmotic stress. It associates with CCM1 in the signaling cascades that regulate vascular integrity and participates in HEG1 (the transmembrane receptor heart of glass 1) mediated endothelial cell junctions. CCM proteins also inhibit the activation of small GTPase RhoA and its downstream effector Rho kinase (ROCK) to limit vascular permeability. CCM2 mediates TrkA-dependent cell death via its N-terminal PTB domain in pediatric neuroblastic tumours. CCM2 possesses an N-terminal PTB domain. The C-terminal domain of malcavernin, which is represented here, appears similar to the N-terminal domain of the scaffolding protein harmonin. It has also been referred to as the Karet domain.
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