Protein Domain : Folliculin/SMCR8, tripartite DENN domain IPR037521

Type	Domain
Description	The tripartite DENN (after differentially expressed in neoplastic versus normal cells) domain is found in several proteins that share common structural features and have been shown to be guanine nucleotide exchange factors (GEFs) for Rab GTPases, which are regulators of practically all membrane trafficking events in eukaryotes. The tripartite DENN domain is composed of three distinct modules which are always associated due to functional and/or structural constraints: upstream DENN or uDENN (also known as longin domain), the better conserved central or core or cDENN, and downstream or dDENN regions. The tripartite DENN domain is found associated with other domains, such as RUN, PLAT, PH, PPR, WD-40, GRAM or C1. The function of DENN domain remains to date unclear, although it appears to represent a good candidate for a GTP/GDP exchangeactivity [ , , , , ].The DENN domain forms a heart-shaped structure, with the N-terminal residues forming one and the C-terminal residues forming the second one. The N-terminal half forms the uDENN domain and consists of a central antiparallel β-sheet layered between one helix and two helices. A long random-coil region links the two lobes. The C-terminal lobe is composed of the cDENN and dDENN domains. The cDENN domain is an alpha/beta three layered sandwich domain with a central sheet of 5-strands. The dDENN domain is an all-alpha helical domain, whose core contains two alpha-hairpins which diverge rapidly in sequence [, ].Divergent types of the tripartite DENN domain have also been detected in other protein families [ ], such as folliculin (FLCN), a tumour suppressor protein disrupted in various cancers and the Birt-Hogg-Dube syndrome, and Smith-Magenis syndrome chromosomal region candidate eight protein (SMCR8), which has been implicated in autophagy [, , ].
Short Name	FLCN/SMCR8_DENN