T cell maturation stage-linked heterogeneity of the glycosylphosphatidylinositol membrane anchor of Thy-1.
We showed that some of Thy-1 molecules on murine thymocytes are resistant to phosphatidylinositol-specific phospholipase C (PI-PLC) derived from Bacillus thuringiensis. Both immature thymocytes with low CD3 expression and mature thymic T lymphocytes with high CD3 expression carried the PI-PLC-resistant Thy-1, and the PI-PLC-sensitivity of Thy-1 extensively varied among thymocyte subpopulations. In contrast, the same PI-PLC fully hydrolysed the anchor of Thy-1 on peripheral T lymphocytes. When the latter cells were activated with mitogen in vitro, however, some Thy-1 on them became resistant to PI-PLC. We then found that virtually all Thy-1 molecules on thymocytes became sensitive to PI-PLC when they were treated with hydroxylamine that should cleave ester-linked lipids. The result ruled out the possibility that the PI-PLC-resistant Thy-1 had a transmembranous peptide sequence, and suggested the presence of an additional fatty acyl group on the inositol ring of the Thy-1 anchor. In addition, the molecular size of the PI-PLC-resistant membrane-bound Thy-1 was only marginally larger than that of the PI-PLC-sensitive solubilized Thy-1 in detergent-partitioning SDS-PAGE analysis.
Department of Immunology, Nagoya University School of Medicine, Aichi, Japan.
I
I
Nakashima
T
T
Yoshida
Y H
YH
Zhang
M Y
MY
Pu
R
R
Taguchi
H
H
Ikezawa
K
K
Isobe
T
T
Iwamoto
M
M
Kato
T
T
Lwin
D000818:Animals; D000954:Antigens, Surface / Q000737:chemistry*; D001426:Bacterial Proteins / Q000378:metabolism; D017261:Glycosylphosphatidylinositols / Q000032:analysis*; D019811:Hydroxylamine; D006898:Hydroxylamines / Q000494:pharmacology; D008562:Membrane Glycoproteins / Q000737:chemistry*; D051379:Mice; D008809:Mice, Inbred C3H / Q000378:metabolism; D043265:Phosphatidylinositol Diacylglycerol-Lyase; D054801:Phosphoinositide Phospholipase C; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D013601:T-Lymphocytes / Q000737:chemistry / Q000166:cytology* / Q000187:drug effects; D018800:Thy-1 Antigens
D000954:Antigens, Surface; D001426:Bacterial Proteins; D017261:Glycosylphosphatidylinositols; D006898:Hydroxylamines; D008562:Membrane Glycoproteins; D018800:Thy-1 Antigens; D019811:Hydroxylamine; D010727:Phosphoric Diester Hydrolases; D054801:Phosphoinositide Phospholipase C; D043265:Phosphatidylinositol Diacylglycerol-Lyase