Identification of an Early Endosomal Protein Regulated by Phosphatidylinositol 3-Kinase

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 94; no. 14; pp. 7326 - 7330
• Main Authors: Patki, Varsha, Virbasius, Joe, Lane, William S., Toh, Ban-Hock, Shpetner, Howard S., Corvera, Silvia
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences of the United States of America 08.07.1997; National Acad Sciences; National Academy of Sciences; The National Academy of Sciences of the USA
• Subjects: 3T3 Cells; Adipocytes; Amino Acid Sequence; Androstadienes - pharmacology; Animals; Antiserum; Biological Sciences; Cell membranes; Cells; Cellular biology; Cytosol; Endosomes; Endosomes - metabolism; Enzyme Inhibitors - pharmacology; Liposomes; Membrane proteins; Membranes; Memory interference; Mice; Molecular Sequence Data; Phosphatidylinositol 3-Kinases; Phosphatidylinositols; Phosphotransferases (Alcohol Group Acceptor) - antagonists & inhibitors; Phosphotransferases (Alcohol Group Acceptor) - metabolism; Proteins; Proteins - metabolism; Wortmannin
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.94.14.7326

Phosphatidylinositol 3-kinases (PI 3-kinases) have been implicated in membrane trafficking in the secretory and endocytic pathways of yeast and mammalian cells, but the molecular mechanisms by which these lipid kinases operate are not known. Here we identify a protein of 170 kDa that is rapidly released from cell membranes in response to wortmannin, a potent inhibitor of mammalian PI 3-kinases. The amino acid sequence of peptides from p170 reveal its identity to early endosomal antigen (EEA) 1, an endosomal antigen with homology to several yeast proteins genetically implicated in membrane trafficking. Immunofluorescence analysis of 3T3-L1 adipocytes with antisera against p170/EEA1 reveal a punctate peripheral pattern that becomes diffuse in response to wortmannin. In vitro, p170/EEA1 binds specifically to liposomes containing PIns(3)P, suggesting that the effect of wortmannin on cells is due to inhibition of PIns(3)P production. Thus, p170/EEA1 may define a family of proteins that mediate the regulatory effects of 3′-phosphoinositides on membrane trafficking in yeast and mammalian cells.