The B cell surface protein CD72 recruits the tyrosine phosphatase SHP-1 upon tyrosine phosphorylation.
Activation signals of lymphocytes are negatively regulated by the membrane molecules carrying the immunoreceptor tyrosine-based inhibition motif (ITIM). Upon tyrosine phosphorylation, ITIMs recruit SH2-containing phosphatases such as SHP-1, resulting in down-modulation of cell activation. We showed that the cytoplasmic domain of the CD72 molecule carries an ITIM and is associated in vitro with SHP-1 upon tyrosine phosphorylation. Moreover, cross-linking of B cell Ag receptor (BCR) enhances both tyrosine phosphorylation of CD72 and association of CD72 with SHP-1 in B cell line WEHI-231. These results indicate that CD72 recruits SHP-1 upon tyrosine phosphorylation induced by BCR signaling, suggesting that CD72 is a negative regulator of BCR signaling.
Adachi
T
T
Department of Immunology, Medical Research Institute, Tokyo Medical and Dental University, Japan.
Flaswinkel
H
H
Yakura
H
H
Reth
M
M
Tsubata
T
T
D000818:Animals; D015703:Antigens, CD / Q000502:physiology*; D000944:Antigens, Differentiation, B-Lymphocyte / Q000502:physiology*; D047908:Intracellular Signaling Peptides and Proteins; D051379:Mice; D010766:Phosphorylation; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases / Q000502:physiology*; D011947:Receptors, Antigen, B-Cell / Q000502:physiology; D014407:Tumor Cells, Cultured; D014443:Tyrosine / Q000378:metabolism*
D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; C064228:CD72 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D011947:Receptors, Antigen, B-Cell; D014443:Tyrosine; C516724:PTPN11 protein, human; C509249:PTPN6 protein, human; D054592:Protein Tyrosine Phosphatase, Non-Receptor Type 11; D053824:Protein Tyrosine Phosphatase, Non-Receptor Type 6; D017027:Protein Tyrosine Phosphatases; C516725:Ptpn11 protein, mouse; C509248:Ptpn6 protein, mouse