Spontaneous phosphorylation of the receptor with high affinity for IgE in transfected fibroblasts.
Receptors with high affinity for IgE, FcepsilonRI, which had been transfected into Chinese hamster ovary fibroblasts exhibit an over 20-fold greater spontaneous phosphorylation at physiological temperatures than the same receptors on the widely studied rat mucosal mast cell line, RBL-2H3. This enhanced phosphorylation was not accounted for either by changes in the src-family kinase responsible for the phosphorylation, by reduced activity of phosphatases, or by spontaneous association of the receptors with microdomains. A variety of approaches failed to detect evidence for stable spontaneous aggregates of the receptor. Whereas the altered posttranslational glycosylation of the receptor's principal ectodomain we detected could promote transient spontaneous aggregation and explain the observed effect, other changes in the membrane milieu cannot be excluded. The functional consequences of such spontaneous phosphorylation are considered.
Torigoe
C
C
Section on Chemical Immunology, Arthritis and Rheumatism Branch, NIAMS, NIH, Bethesda, Maryland 20892-1820, USA.
Metzger
H
H
D000595:Amino Acid Sequence; D000818:Animals; D016466:CHO Cells; D002999:Clone Cells; D006224:Cricetinae; D004735:Energy Transfer / Q000235:genetics; D004789:Enzyme Activation / Q000235:genetics; D005347:Fibroblasts / Q000166:cytology / Q000201:enzymology / Q000276:immunology / Q000378:metabolism*; D007399:Interphase / Q000235:genetics; D021962:Membrane Microdomains / Q000235:genetics / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D051381:Rats; D017455:Receptors, IgE / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism*; D013050:Spectrometry, Fluorescence; D013696:Temperature; D014162:Transfection; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism; D019061:src-Family Kinases / Q000235:genetics / Q000378:metabolism
D017455:Receptors, IgE; D014443:Tyrosine; C060902:lyn protein-tyrosine kinase; D019061:src-Family Kinases; D010744:Phosphoric Monoester Hydrolases