In this issue: Proteomics 4/2009

In this issue of Proteomics you will find the following highlighted articles: APE1: An 800 pound (360 kg) gorilla in our cells? APE1 has been around for a while, recognized as a component of the DNA excision repair machinery, involved in cleanup of apurinic and apyrimidinic sites that result from radiation damage to the bases. More recently it has also been assigned a role as a redox transcriptional co‐activator. In this paper, Vascotto et al. look deeper into this second function and find that APE1 is not just a minor player in mammalian cells, it also has a significant role in genomic stability. Using siRNA technology, they looked at genome wide transcription and proteomic responses to changes in APE1 levels. This approach indicated that this protein has a part in cell growth, apoptosis, intracellular redox state, mitochondrial function and cytoskeletal structure. Given this scope of function, what the APE says, goes. Vascotto et al. , Proteomics 2009, 9 , 1058–1074. Slippin' and a‐slidin'... If you are a bacterium, those are most of your options for getting around on the dance floor unless you have pili – then you can be a‐glidin' (unless someone has stuck some mutations in your pilus genes). That's what Kim et al. did to a strain of cyanobacteria ( Synechocystis ) to dissect the post‐translational glycosylation of the pilA1 gene product. PilA1 encodes the principal structural protein for the thick type of pili. Using a variety of tools, they were able to show that this non‐pathogenic bacterium used post translational modification (glycosylation) apparently to regulate surface adhesiveness or mobility. Low mobility mutants had additional hexoses inserted into the O‐linked wild‐type glycan. Kim et al., Proteomics 2009, 9 , 1075–1086. Double‐stranded barbed wire for blood‐brain barrier? The blood‐brain barrier (BBB) and barbed wire have at least one thing in common: their function. They keep things in their places, cows and immunoglobulins stay on one side, rabbits and glucose cross at will, all deer and toxins keep out. We have a pretty good idea of how barbed wire works but the BBB has been much more of a challenge. Agarwal and Shusta have developed a multiplexed expression cloning system in mammalian cells which makes it possible to identify both structural and functional BBB membrane proteins. After four rounds of enrichment, 121 cDNA clones were isolated, yielding 30 that were recognized by fluorescent anti‐BBB antibodies, of which 15 were unique. A number of mitochondrial proteins were found, including ND4, highly hydrophobic with a predicted 12 transmembrane segments. Agarwal et al., Proteomics 2009, 9 , 1099–1108.