Rapid dephosphorylation of the GTPase dynamin after FcepsilonRI aggregation in a rat mast cell line.
As part of our studies aimed at exploring the potential role(s) of protein phosphatases in mast cell signaling, we analyzed the phosphorylation status of tyrosine-containing proteins in a rat mast (RBL) cell line that expresses both native rat high affinity IgE receptors (FcepsilonRI) and functional human FcepsilonRIalpha. After FcepsilonRI aggregation, there was a rapid increase in the tyrosine phosphorylation of a number of proteins, including those of m.w. 72 and 110 kDa. Concurrent with these events, however, there was a rapid dephosphorylation of a 100-kDa protein that was constitutively phosphorylated in the unstimulated cells. Using a specific mAb, this 100-kDa protein was identified as the GTPase dynamin. Dynamin was shown to associate with the SH3 domain of the src-related tyrosine kinase p56lyn in RBL 2H3 cells both in vitro and in vivo. FcepsilonRI aggregation causes rapid internalization of the aggregated receptors via clathrin-coated pits and dynamin is known to play a role in clathrin-mediated endocytosis, so the dephosphorylation of dynamin may provide the signal for targeting the aggregated receptors to the endocytic pathway.
Pullar
C E
CE
Department of Inflammation and Autoimmune Diseases, Hoffmann-La Roche, Inc., Nutley, NJ 07110, USA.
Repetto
B
B
Gilfillan
A M
AM
D000818:Animals; D002478:Cells, Cultured; D034281:Dynamins; D004591:Electrophoresis, Polyacrylamide Gel; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D006801:Humans; D008407:Mast Cells / Q000166:cytology* / Q000378:metabolism; D008970:Molecular Weight; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000032:analysis; D011233:Precipitin Tests; D051381:Rats; D011940:Receptor Aggregation; D017455:Receptors, IgE / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000378:metabolism; D019061:src-Family Kinases / Q000378:metabolism
D017455:Receptors, IgE; D013438:Sulfhydryl Compounds; D019000:Phosphotyrosine; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D020558:GTP Phosphohydrolases; D034281:Dynamins