In 2007, the International Knockout Mouse Consortium (IKMC) made the ambitious promise to generate mutations in virtually every protein-coding gene of the mouse genome in a concerted worldwide action. Now, 5 years later, the IKMC members have developed high-throughput gene trapping and, in particular, gene-targeting pipelines and generated more than 17,400 mutant murine embryonic stem (ES) cell clones and more than 1,700 mutant mouse strains, most of them conditional. A common IKMC web portal (www.knockoutmouse.org) has been established, allowing easy access to this unparalleled biological resource. The IKMC materials considerably enhance functional gene annotation of the mammalian genome and will have a major impact on future biomedical research.

The penicillin-binding proteins (PBPs) are a set of enzymes responsible for the terminal stages of peptidoglycan biosynthesis, where they carry out transpeptidation, transglycosylation, endopeptidase, or carboxypeptidase functions. It is the transpeptidation, endopeptidase, and carboxypeptidase functions that are inhibited when these proteins are acylated by a ␤-lactam antibiotic (10). In all cases where this reaction has been investigated biochemically, the ␤-lactam ring opens and forms a covalent bond with an active-site serine residue on the PBP (10, 11). Among the most extensively investigated PBPs are those of the gram-negative bacillus Escherichia coli, and these have been the subject of numerous publications and reviews. It is for E. coli that we have perhaps the clearest understanding of the roles that the individual PBPs perform in peptidoglycan synthesis and cell morphogenesis (7,19,21). At the same time, however, much remains to be understood concerning the role of the PBPs in cell wall growth and their participation in cell division.More than 18 years ago, Spratt published an estimate of the numbers of individual PBPs in an average E. coli cell (25). In this seminal work, the PBPs of isolated cell membranes were labeled with [ 14 C]penicillin and separated by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis. After electrophoresis, the radiolabeled PBPs were detected by fluorography. The numbers of PBPs per cell were calculated by scanning fluorographs, obtaining the areas under the curves and calculating a percentage distribution for each of the individual PBPs. This relative distribution was then combined with a literature value for the total amount of [ 14 C]cefoxitin bound per milligram (dry weight) and a literature value for cell number per milligram (dry weight) to arrive at absolute values of individual PBP numbers per cell (20,25). Although this was clearly meant as a rough estimate, this set of numbers has been cited repeatedly in numerous publications and several textbooks since that time (1,7,19,21,26).Because of the importance of these proteins in ␤-lactam antibiotic action, cell wall assembly, and cell division, we decided to measure the numbers of the individual PBPs of E. coli by a direct method. In the present study, the numbers of molecules per cell of the individual PBPs were calculated directly by measuring both the cell numbers present and the radioactivity in the individual PBPs from a precise quantity of cells. Care was taken to ensure that the individual PBPs were saturated with [ 3 H]penicillin, and a sufficiently large number of samples were taken in separate experiments to allow statistical assessment of the data sets. The results obtained in the present study are in some cases significantly different from the previously published values. In addition, measurements were performed with both rapidly growing cells in Luria broth (LB) medium as well as with cells growing in M9 minimal medium. The absolute numbers of PBPs were reduced in the cells growing at a lower ...

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Policies supporting the rapid and open sharing of genomic data have directly fueled the accelerated pace of discovery in large-scale genomics research. The proteomics community is starting to implement analogous policies and infrastructure for making large-scale proteomics data widely available on a pre-competitive basis. On August 14, 2008, the National Cancer Institute (NCI) convened the “International Summit on Proteomics Data Release and Sharing Policy” in Amsterdam, the Netherlands, to identify and address potential roadblocks to rapid and open access to data. The six principles agreed upon by key stakeholders at the summit addressed issues surrounding 1) timing, 2) comprehensiveness, 3) format, 4) deposition to repositories, 5) quality metrics, and 6) responsibility for proteomics data release. This summit report explores various approaches to develop a framework of data release and sharing principles that will most effectively fulfill the needs of the funding agencies and the research community.