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An arachidonic acid-stimulated Ser/Thr phosphatase activity was detected in soluble extracts prepared from rat pituitary clonal GH4C1 cells, rat or bovine brain, and bovine heart. The enzyme activity was purified to homogeneity from bovine brain as a monomer with a Mr of 63,000 and a specific activity of 32 nmol of Pi released per min/mg of protein when(More)
We describe functional simplified T cell and Fc receptor chimeras that are capable of directing CD8+ cytotoxic T lymphocytes (CTLs) to specifically recognize and lyse cells expressing HIV envelope proteins. Target cells bearing HLA-DR molecules are not recognized by CTL armed with the chimeras. The variety of cell types in which the native receptors are(More)
The Syk family tyrosine kinases play a crucial role in antigen receptor-mediated signal transduction, but their regulation and cellular targets remain incompletely defined. Following receptor engagement, phosphorylation of tyrosine residues within ZAP-70 and Syk is thought to control both kinase activity and recruitment of modulatory factors. We report here(More)
In this paper we study mergers in two-sided industries and, in particular, the effects of mergers in the newspaper industry. We present a model which shows that mergers in two-sided markets may not necessarily lead to higher prices for either side of the market. We test our conclusions by examining a spate of mergers in the Canadian newspaper industry in(More)
The zeta chain of the T cell antigen receptor is a dimeric transmembrane protein with a very short extracellular domain and an extended cytoplasmic tail that triggers T cell effector function when aggregated by extracellular stimuli. We have reduced the active site of zeta to an 18 residue motif that can be appended to the intracellular domain of other(More)
An emerging theme in immunology finds receptors which initiate cellular effector programs forming multichain complexes in which the ligand recognition elements associate with one or more 'trigger molecules' whose aggregation initiates a signal transduction cascade. The sequence motifs constituting the active sites of these trigger molecules are found in the(More)
The pharmaceutical industry is characterized as having substantial investment in R&D and a large number of new product introductions, which poses special problems for price measurement caused by the quality of drug products changing over time. This paper applies recent demand estimation techniques to individual level data to construct a constant-quality(More)
Protein kinases and phosphatases play an important role in signal transduction. In the T cell, activation via the T cell receptor-CD3 complex results in rapid tyrosine phosphorylation of proteins, as well as subsequent increases in serine/threonine phosphorylation. The Raf serine/threonine kinase has been implicated in many receptor signaling pathways,(More)