All three PACSIN isoforms bind to endocytic proteins and inhibit endocytosis.
The PACSINs are a family of cytoplasmic phosphoproteins that play a role in vesicle formation and transport. We report the cloning and cDNA sequencing of PACSIN 3 and the analysis of all three PACSIN isoforms with regard to tissue distribution, ligand binding properties and influence on endocytosis. PACSIN 3 differs from the other family members in having a short proline-rich region and lacking asparagine-proline-phenylalanine motifs. In contrast to the neurospecific PACSIN 1 and the ubiquitously expressed PACSIN 2, PACSIN 3 is mainly detected in lung and muscle tissues. All isoforms potentially oligomerize and bind to dynamin, synaptojanin 1 and N-WASP via their Src homology 3 domains. The PACSIN proteins colocalize with dynamin, but not with clathrin, implying a specific role with a distinct subpopulation of dynamin at defined cellular sites. Transferrin endocytosis is blocked in a dose-dependent manner in cells overexpressing the PACSIN variants, but the inhibitory effect can be abolished by mutating specific amino acid residues in the Src homology 3 domains. These characteristics of the PACSIN protein family suggest a general function in recruitment of the interacting proteins to sites of endocytosis.
Modregger
J
J
Institute for Biochemistry II, Medical Faculty, University of Cologne, D-50931 Cologne, Germany.
Ritter
B
B
Witter
B
B
Paulsson
M
M
Plomann
M
M
D048868:Adaptor Proteins, Signal Transducing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003598:Cytoskeletal Proteins; D018076:DNA, Complementary; D034281:Dynamins; D004705:Endocytosis / Q000502:physiology*; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D014018:Tissue Distribution; D014168:Transferrin / Q000378:metabolism; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal
D048868:Adaptor Proteins, Signal Transducing; D003598:Cytoskeletal Proteins; D018076:DNA, Complementary; D047908:Intracellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; C120714:PACSIN2 protein, human; C421762:PACSIN3 protein, human; C485644:Pacsin2 protein, mouse; C486019:Pacsin3 protein, mouse; D010750:Phosphoproteins; D020033:Protein Isoforms; D011506:Proteins; D014168:Transferrin; C495771:WASL protein, human; C495772:Wasl protein, mouse; D051317:Wiskott-Aldrich Syndrome Protein, Neuronal; C097702:synaptojanin; D010744:Phosphoric Monoester Hydrolases; D020558:GTP Phosphohydrolases; D034281:Dynamins