Example of SDS-PAGE of proteins visualized by autoradiography. Two radioactively labeled protein samples were run in adjacent lanes of the gel (1, 2). The larger proteins (β-galactosidase size standard, marker, E-cadherin cell-to-cell adhesion protein, pp120) are towards the top of the gel and smaller proteins (vSRC tyrosine-specific protein kinase, 60,000 Da) are towards the bottom. As its name implies, pp120 is a 120,000 Da phosphoprotein. The β-galactosidase and bovine serum albumin (BSA) size standards were in an adjacent lane (not shown). The radioactive label was 32Phosphate from the gamma position phosphate group of ATP. The vSRC protein is an oncogene that disrupts cellgrowth by its phosphorylation of other proteins such as β-catenin, a protein that links E-cadherin to the cell's cytoskeleton. In this experiment, the vSRC protein auto-phosphorylated itself and the other proteins (E-cadherin, pp120 and β-catenin). After electrophoresis, medical X-ray film was exposed to the dried gel and regions of dark exposure of the film (the "bands") indicate the position of the radioactively-labeled proteins. Lane 1 is a negative control for which no vSRC was added to the labeling reaction. The other proteins (E-cadherin, pp120 and β-catenin) came from an immunoprecipitation of E-cadherin with anti-E-cadherin antibody. The pp120 and β-catenin proteins exist in a molecular complex with E-cadherin at the surface of the cell and they co-precipitate with E-cadherin. Some cSRC kinase probably also co-precipitated with the E-cadherin, accounting for the faint bands in lane 1. The vSRC kinase was immunoprecipitated from mouse NIH-3T3 cells that had been genetically engineered to express this chicken-derived oncogene. The E-cadherin was from mouse P19 embryonal carcinoma cells. (this picture was worth 290 words)
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From English Wikipedia: http://en.wikipedia.org/w/index.php?title=Image:SDSPAGE.png&action=edit Example of SDS-PAGE of proteins visualized by autoradiography. Two radioactively labeled protein samples were run in adjacent lanes of the gel (1, 2). The la