During or immediately after synthesis in vertebrate cells, the oncogenic protein-tyrosine kinase pp6Ov-sm associates with the =90-kDa heat-shock protein (hsp9O). In this complex, pp6Ov-src is not functional as a kinase. When pp6Ov-src is subsequently found inserted into the plasma membrane, it is active as a kinase and is no longer associated with hsp9O. We have taken advantage of genetic manipulations possible in Saccharomyces cerevisiae to investigate the function and specificity of the association between hsp9O and pp6Ovsrc. Expression of pp6Ovsrc is known to be toxic to S. cerevisiae cells. We rind that this toxicity is due to a very specific effect on growth, arrest at a particular point in the cell cycle. In cells expressing v-src, a mutation that lowers the level of hsp9O expression (i) relieves cell cycle arrest and rescues growth, (it) reduces the level of tyrosine phosphorylation mediated by pp6Ov-src, (iii) changes the pattern of tyrosine phosphorylation, and (iv) reduces the concentration of pp6Ovsrc. We conclude that hsp9O does not simply suppress pp6Ov-src kinase activity during transit to the plasma membrane, as previously suggested, but also stabilizes the protein and affects both its activity and specificity. This function of hsp9O is highly selective for pp60v-src: the same hsp9O mutation has no effect on the activity or specificity of the exogenous ppl6Ov

Material Supplementary 4.DC1http://www.jimmunol.org/content/suppl/2010/06/16/jimmunol.090387

The identity of the earliest inhabitants of Xinjiang, in the heart of Inner Asia, and the languages that they spoke have long been debated and remain contentious1. Here we present genomic data from 5 individuals dating to around 3000–2800 bc from the Dzungarian Basin and 13 individuals dating to around 2100–1700 bc from the Tarim Basin, representing the earliest yet discovered human remains from North and South Xinjiang, respectively. We find that the Early Bronze Age Dzungarian individuals exhibit a predominantly Afanasievo ancestry with an additional local contribution, and the Early–Middle Bronze Age Tarim individuals contain only a local ancestry. The Tarim individuals from the site of Xiaohe further exhibit strong evidence of milk proteins in their dental calculus, indicating a reliance on dairy pastoralism at the site since its founding. Our results do not support previous hypotheses for the origin of the Tarim mummies, who were argued to be Proto-Tocharian-speaking pastoralists descended from the Afanasievo1,2 or to have originated among the Bactria–Margiana Archaeological Complex3 or Inner Asian Mountain Corridor cultures4. Instead, although Tocharian may have been plausibly introduced to the Dzungarian Basin by Afanasievo migrants during the Early Bronze Age, we find that the earliest Tarim Basin cultures appear to have arisen from a genetically isolated local population that adopted neighbouring pastoralist and agriculturalist practices, which allowed them to settle and thrive along the shifting riverine oases of the Taklamakan Desert.

Although Hsp90 displays general chaperone activity in vitro, few substrates of the chaperone have been identified in vivo, and the characteristics that render these substrates dependent on Hsp90 remain elusive. To investigate this issue, we exploited a paradoxical observation: several unrelated oncogenic viral tyrosine kinases, including v-src, attain their native conformation after association with Hsp90, yet their nearly identical cellular homologs interact only weakly with the chaperone. It has been controversial whether Hsp90 is vital for normal maturation of the cellular kinases or is simply binding a misfolded subfraction of the proteins. By modulating Hsp90 levels in Saccharomyces cerevisiae, we determined that Hsp90 is indeed necessary for the maturation of c-src (the normal homolog of v-src). c-src maturation is, however, less sensitive to Hsp90 perturbations than is v-src maturation. Dependence of the two proteins on Hsp90 does not correspond to their relative efficiency in reaching their final destination (the plasma membrane); we observed that in yeast, unlike in vertebrate cells, neither c-src nor v-src concentrate in the membrane. Expression of different v͞c-src chimeras in cells carrying wild-type or temperature-sensitive Hsp90 alleles revealed that the difference between the proteins instead arises from multiple, naturally occurring mutations in the C-terminal region of v-src.

Protein acetylation catalyzed by specific histone acetyltransferases (HATs) is an essential posttranslational modification (PTM) and involved in the regulation a broad spectrum of biological processes in eukaryotes. Although several ten thousands of acetylation sites have been experimentally identified, the upstream HATs for most of the sites are unclear. Thus, the identification of HAT-specific acetylation sites is fundamental for understanding the regulatory mechanisms of protein acetylation. In this work, we first collected 702 known HAT-specific acetylation sites of 205 proteins from the literature and public data resources, and a motif-based analysis demonstrated that different types of HATs exhibit similar but considerably distinct sequence preferences for substrate recognition. Using 544 human HAT-specific sites for training, we constructed a highly useful tool of GPS-PAIL for the prediction of HAT-specific sites for up to seven HATs, including CREBBP, EP300, HAT1, KAT2A, KAT2B, KAT5 and KAT8. The prediction accuracy of GPS-PAIL was critically evaluated, with a satisfying performance. Using GPS-PAIL, we also performed a large-scale prediction of potential HATs for known acetylation sites identified from highthroughput experiments in nine eukaryotes. Both online service and local packages were implemented, and GPS-PAIL is freely available at: http://pail.biocuckoo.org.As one of the most important and ubiquitous post-translational modifications (PTMs) in proteins, the lysine acetylation catalyzed by histone acetyltransferases (HATs) or lysine acetyltransferases (KATs) reversibly regulates a large number of biological processes, such as transcriptional regulation, metabolism and autophagy [1][2][3][4][5][6][7] . The dysregulation of site-specific HAT-substrate relations is frequently associated with human diseases such as cancers 2,3,8,9 . In eukaryotes, numerous HATs have been classified into three major families including p300/CBP, GCN5-related N-acetyltransferases (GNATs) and MYST proteins 1-3,10,11 . Different HATs can recognize overlapping but distinct substrates 1,11,12 . Most HATs exist in multisubunit complexes in vivo by physically interacting with non-catalytic proteins, which are also involved in recognizing substrates and synergistically determine the specificity together with HATs 2,3 . In this regard, the identification of HAT-specific acetylation sites in proteins is fundamental for understanding the molecular mechanisms and regulatory roles of lysine acetylation.Previously, systematic identification of protein acetylation sites or "acetylome" was a great challenge, due to the technical limitation 4,13 . For example, in 2006, Kim et al. used