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Abstract

AbstractTruckin' down the road with a load and then it's back ag'inIt sounds like a Grateful Dead song, but it's not. It's what certain protein tracking organelles do to maintain structure and polarity of the cell they reside in. ATP‐powered kinesin motors, calsyntenin‐docking equipment, coat proteins, tethering factors and small GTPases all have a role to play in emplacing membrane segments for axonal development and repair. Steuble et al. examine the components that comprise the calsyntenin‐1 complex by immunoisolation from mouse brain and identification by mass spectrometry. Among their findings were β‐amyloid precursor protein and two non‐overlapping transport packages: one for early steps, the second for recycling some of the endosomal components.pp. 3775–3788Multiple personalities from multiple formsThe basic tenet of molecular biology “one gene–one protein” has suffered some restructuring over the past few years. Depending on the mRNA splicing pattern, several proteins can be derived from the same gene core and the post‐translational modification pattern; one protein can select one of several targets for post‐translational modification. Kimura et al. examined the multiple forms of heterogeneous nuclear ribonucleoprotein K: it can be spliced multiple ways and phosphorylated at either of two sites. They used a new proteomics tool for phosphorylation studies: phosphate‐affinity gel electrophoresis. The technique co‐polymerizes into the gel (1‐D SDS‐PAGE or 2‐DE) an Mn2+‐Phos‐tag™ ligand that yields a gel capable of resolving phosphoproteins by differences at single phosphorylation sites. The 2‐DE separation of nuclear ribonuclear protein K with the Phos‐tagged second dimension revealed more than 20 beautiful spots.pp. 3884–3895Bio‐markers at the flip of a golden switchELISAs and Western blots are the most common ways of testing the validity of a potential diagnostic bio‐marker, but both are subject to problems of various types and are not conveniently automated for high throughput. Brauer et al. have demonstrated a new way of trapping the antigen, washing the complex, then releasing it electrolytically from a gold electrode. The antigen solution is mixed with MALDI matrix solution and dried down over a hydrophilic target pattern printed on the MALDI plate. As the mixture dries, the antigen within an outer ring is concentrated on the center spot of the target where the matrix also crystallizes. The technique was demonstrated by quantifying transthyretin in human serum.pp. 3922–3927