Tyrosine phosphorylation of alpha tubulin in human T lymphocytes.

N-terminal sequencing of the 55- and 50-kDa polypeptides affinity purified on a phosphotyrosine monoclonal antibody column from activated Jurkat T cells identified alpha and beta tubulin. Two-dimensional gel analysis indicated that alpha tubulin was directly phosphorylated on tyrosine. beta Tubulin was not detectably tyrosine phosphorylated but was precipitated by anti-phosphotyrosine (PTyr) antibody by virtue of its association with the alpha subunit as a heterodimer.

Crystallization and preliminary X-ray crystallographic studies of human placental annexin IV.

Human placental annexin IV, a member of the annexin family of calcium and phospholipid-binding proteins, has been crystallized by the vapour diffusion method in the presence of calcium, using polyethylene glycol 8000. The crystals are orthorhombic, space C222(1), cell dimensions a = 105.4 A, b = 115.

Evidence that protein kinase C differentially regulates the human T lymphocyte CD2 and CD3 surface antigens.

The purpose of the present study was to explore the effects of protein kinase C (PKC) stimulation on two cell surface receptors that regulate T cell growth: the T cell antigen receptor/CD3 complex and the CD2 antigen. The data show that PKC differentially regulates the expression and functions of CD2 and CD3 molecules. Thus, activation of PKC induced a decrease in cell surface levels of CD3 molecules but an increase in the expression of CD2 antigens.

Purification and identification by amino acid sequence analysis of the subunits of the CD3 antigen of human tonsil T-lymphocytes.

The CD3 antigen was purified from human tonsils by immunoaffinity chromatography and preparative SDS-PAGE; the overall yield was 10%. Amino acid sequence analysis of the separated gamma, delta and epsilon polypeptides revealed that the gamma and epsilon polypeptides were blocked at the N-terminus, whereas the partial N-terminal amino acid sequence for the delta chain was identical to that described by Borst et al. [Nature 312, 455-485 (1984)].