Longin is one of the approximately 26 components required for transporting proteins from the ER to the plasma membrane, via the Golgi apparatus. It is necessary for the steps of the transfer from the ER to the Golgi complex (PUBMED:16855025). Longins are the only R-SNAREs that are common to all eukaryotes, and they are characterised by a conserved N-terminal domain with a profilin-like fold called a longin domain (PUBMED:15544955).
VAMPs (and its homologue synaptobrevins) define a group of SNARE proteins that contain a C-terminal coiled-coil/SNARE domain, in combination with variable N-terminal domains that are used to classify VAMPs: those containing longin N-terminal domains (~150 aa) are referred to as longins, while those with shorter N-termini are referred to as brevins [ (PUBMED:12914952) ]. Longins are the only type of VAMP protein found in all eukaryotes, suggesting that their longin domain is essential. The longin domain is thought to exert a regulatory function. Longin domains have been shown to share the same structural fold, a profilin-like globular domain consisting of a five-stranded antiparallel beta-sheet that is sandwiched by an alpha-helix on one side, and two alpha-helices on the other (beta(2)-alpha-beta(3)-alpha(2)).
Family alignment:
There are 6851 Longin domains in 6843 proteins in SMART's nrdb database.
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Evolution (species in which this domain is found)
Taxonomic distribution of proteins containing Longin domain.
This tree includes only several representative species. The complete taxonomic breakdown of all proteins with Longin domain is also avaliable.
Click on the protein counts, or double click on taxonomic names to display all proteins containing Longin domain in the selected taxonomic class.
Identification of the yeast R-SNARE Nyv1p as a novel longin domain-containingprotein.
Mol Biol Cell. 2006; 17: 4282-99
Display abstract
Using nuclear magnetic resonance spectroscopy, we establish that the N-terminaldomain of the yeast vacuolar R-SNARE Nyv1p adopts a longin-like fold similar tothose of Sec22b and Ykt6p. Nyv1p is sorted to the limiting membrane of thevacuole via the adaptor protein (AP)3 adaptin pathway, and we show that itslongin domain is sufficient to direct transport to this location. In contrast, wefound that the longin domains of Sec22p and Ykt6p were not sufficient to directtheir localization. A YXX phi-like adaptin-dependent sorting signal (Y31GTI34)unique to the longin domain of Nyv1p mediates interactions with the AP3 complexin vivo and in vitro. We show that amino acid substitutions to Y31GTI34(Y31Q;I34Q) resulted in mislocalization of Nyv1p as well as reduced binding ofthe mutant protein to the AP3 complex. Although the sorting of Nyv1p to thelimiting membrane of the vacuole is dependent upon the Y31GTI34 motif, and Y31 inparticular, our findings with structure-based amino acid substitutions in the mu chain (Apm3p) of yeast AP3 suggest a mechanistically distinct role for thissubunit in the recognition of YXX phi-like sorting signals.
Crystal structure of the mammalian COPII-coat protein Sec23a/24a complexed with the SNARE protein Sec22 and bound to the transport signal sequence of vesicular stomatitis virus glycoprotein
Crystal structure of the mammalian COPII-coat protein Sec23a/24a complexed with the SNARE protein Sec22b and bound to the transport signal sequence of the SNARE protein Bet1
