Gaf-1, a gamma -SNAP-binding protein associated with the mitochondria.

The role of alpha/beta-SNAP (Soluble NSF Attachment Protein) in vesicular trafficking is well established; however, the function of the ubiquitously expressed gamma-SNAP remains unclear. To further characterize the cellular role of this enigmatic protein, a two-hybrid screen was used to identify new, gamma-SNAP-binding proteins and to uncover potentially novel functions ...
for gamma-SNAP. One such SNAP-binding protein, termed Gaf-1 (gamma-SNAP associate factor-1) specifically binds gamma- but not alpha-SNAP. The full-length Gaf-1 (75 kDa) is ubiquitously expressed and is found stoichiometrically associated with gamma-SNAP in cellular extracts. This binding is distinct from other SNAP interactions since no alpha-SNAP or NSF coprecipitated with Gaf-1. Subcellular fractionation and immunofluorescence analysis show that Gaf-1 is peripherally associated with the outer mitochondrial membrane. Only a fraction of gamma-SNAP was mitochondrial with the balance being either cytosolic or associated with other membrane fractions. GFP-gamma-SNAP and the C-terminal domain of Gaf-1 both show a reticular distribution in HEK-293 cells. This reticular structure colocalizes with Gaf-1 and mitochondria as well as with microtubules but not with other cytoskeletal elements. These data identify a class of gamma-SNAP interactions that is distinct from other members of the SNAP family and point to a potential role for gamma-SNAP in mitochondrial dynamics.
Mesh Terms:
Adaptor Proteins, Signal Transducing, Carrier Proteins, Cell Line, Cytosol, Humans, Intracellular Membranes, Kinetics, Membrane Proteins, Mitochondria, Mitochondrial Proteins, Recombinant Proteins, Saccharomyces cerevisiae, Soluble N-Ethylmaleimide-Sensitive Factor Attachment Proteins, Substrate Specificity, Transfection, Tubulin, Vesicular Transport Proteins
J. Biol. Chem.
Date: Apr. 20, 2001
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