Simultaneous electrophoretic analysis of proteins of very high and low molecular weights using low-percentage acrylamide gel and a gradient SDS-PAGE gel

To be able to separate and analyze giant proteins and small proteins in the same elec-trophoretic gel, we have used a continuous SDS-PAGE gel formed by the combinationof a low-percentage acrylamide gel and a gradient SDS-PAGE gel that we have namedLAG gel. To get a good resolution for proteins of more than 200 kDa, we used anacrylamide/bisacrylamide ratio of 80:1 in the low-percentage acrylamide gel. To suc-cessfully resolve proteins in the 5–200 kDa range, we used a conventional 6–15%SDS-PAGE gradient gel with the standard acrylamide/bisacrylamide ratio of 40:1. Weshow that the LAG system can be successfully used in general applications of SDS-PAGE electrophoresis such as proteomics and immunoblotingtechniques. Thus, usingthiscontinuousLAGgel, itispossibletosimultaneouslyanalyze giantproteins,suchasHERC1 and dynein, big proteins like clathrin heavy chain and small proteins like ARF.The LAG system has a good resolution, low cost, and high reproducibility. Moreover, tosimultaneously analyze all proteins saves time. All these characteristics, together withthe use of a standard apparatus found in any biochemistry laboratory, make the LAGsystem an easy tool to use.