Open AccessHuman spectrin Src homology 3 domain binding protein 1 regulates macropinocytosis in NIH 3T3 cells
Author(s) -
Jiliu Xu,
Dorota Ziemnicka,
George Merz,
Leszek Kotula
Publication year - 2000
Publication title -
journal of cell science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.384
H-Index - 278
eISSN - 1477-9137
pISSN - 0021-9533
DOI - 10.1242/jcs.113.21.3805
Subject(s) - pinocytosis , biology , endocytosis , microbiology and biotechnology , vesicle , sh3 domain , spectrin , endocytic cycle , 3t3 cells , fusion protein , clathrin , proto oncogene tyrosine protein kinase src , biochemistry , transfection , cytoskeleton , phosphorylation , cell , membrane , recombinant dna , gene
Macropinocytosis is an endocytic process that occurs through non-clathrin coated vesicles larger than 0.2 microm in diameter. Although macropinocytic vesicles are readily visualized in cultured cells by the introduction of fluorescent, water-soluble dyes into the culture medium, protein markers associated with this type of vesicles have not yet been well defined. Here, we report that human spectrin SH3 domain binding protein 1, or Hssh3bp1, associates with macropinosomes in NIH 3T3 fibroblasts. Hssh3bp1 macropinosomes are heterogeneous in morphology and size, do not endocytose transferrin and are resistant to brefeldin A treatment. Cytochalasin D, and wortmannin block endocytosis of fluorescent dyes into the Hssh3bp1 macropinosomes and dramatically affect their morphology. Overexpression of Hssh3bp1-green fluorescent protein abolished fusion of vesicles resulting in a decreased endocytosis of fluorescence dyes, thus suggesting a potential regulatory role of Hssh3bp1 in macropinocytosis. In the macropinosomes of NIH 3T3 cells, Hssh3bp1 associates with a 200-kDa protein that crossreacts with a monoclonal antibody to the erythroid alpha-spectrin SH3 domain. Thus macropinosomes in cells may contain a spectrin-like protein.