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Abstract

AbstractProteinaceous politics: dictatorial hierarchy, the king speaks firstpp. 2990–2998Pseudomonas putida is a non‐pathogenic free‐living soil/aquatic Gram‐negative bacterial species, useful as a recombinant DNA host. It is of particular interest because of its selectivity when offered a variety of carbon sources for growth. Selection is exercised through catabolite repression control of particular genes. Moreno et al. found crc gene effects in the expression of 119 proteins (64 unique) by 2‐D DIGE and MALDI‐TOF/TOF. Transcriptome analysis matched 23 of the 64 proteins (p<0.05), or, with reduced statistical stringency (p<0.1), 33. The control is at the level of transport and catabolism. Talk about micromanagement, crc controls branched‐chain ketoacid dehydrogenase and conversion of tyrosine to phenylalanine. It directly and indirectly controls much of the C1‐metabolism as well. With all this control, P. putida can even grow, albeit slowly, on the spent media of other bacteria.magnified imagePhosphotyrosine – the other phosphoamino acidpp. 3047–3057The advertising campaign touting pork as “the other white meat” did pigs a disservice – they never claimed to be able to fly and, besides, what part of a chicken is as tasty as ham or bacon? When it comes to phosphoproteins, it seems that phosphoserine (pS) and phosphothreonine (pT) take most of the glory. Phosphotyrosine (pY) is less frequent and, being unstable at low pH, is more difficult to isolate. The method published here by Condina et al. circumvents many of these problems by using a combination of affinity reagents and paramagnetic beads to avoid precipitation steps. The principal reagent is anti‐pY antibody 4G10. Using various methods of attachment alters the affinity of the antibody for pY, unphosphorylated tyrosine, and pY in peptides. When bound peptides are eluted, the authors report a 200‐fold improvement in peptide detection. And the whole process is readily automated for high throughput. magnified imageThe run for the biomarkerpp. 3058–3065The list of featured articles for this issue hit my in‐box the week before the Kentucky Derby. What are the odds of it including an equine biomarker paper by chance? A puzzle for the statisticians. Horseracing is big business – stud fees can run as high as $200 000+ – so you want to be sure you get what you pay for – genetic speed, not something that came out of a bottle. To reliably detect steroid doping, Barton et al. started by characterizing horse plasma from geldings that had or had not been treated with testosterone. They identified 70 proteins in undepleted plasma which allowed them to develop a targeted multiple reaction monitor (MRM) using 49 of the proteins. Normalization appeared to be a bit more work than usual, but there's always one horse that shys at the gate. magnified image