Search

Cloned cDNAs for the human mitochondrial DNA polymerase γ (POLG) were identified by homology with the yeast mitochondrial DNA polymerase catalytic subunit (MIP). Fluorescence in situ hybridization (FISH) of human and mouse bacterial artificial chromosomes (BACs), hybridized by radioactively labeled POLG cDNAs, mapped to human chromosome band 15q24→q26, as well as to mouse chromosome band 7E. Direct sequencing of the BAC DNA without subcloning confirmed the presence of both human POLG and mouse mitochondrial DNA polymerase γ (Polg) in the respective BACs.

The introduction of silver-staining to detect electrophoretically separated proteins in polyacrylamide gels has provided a method that, with the most responsive proteins, is more sensitive by a factor of ∼100 than Coomassie Blue, the most commonly used organic stain. With silver staining, most proteins take on a brownish hue. However, under appropriate conditions, certain proteins have been found to exhibit distinct and vivid colors. Yellow, blue, red and green bands have all been observed. Colorability is a property with considerable analytical potential, in that it may become possible to infer chemical properties of proteins on the basis of their propensities for coloration upon silver-staining. Such information would considerably enhance the analytical capabilities of gel electrophoresis, which for the most part have been restricted to estimates of molecular weights and isoelectric points. To help realize this potential, we have investigated the physical basis of the colorability of proteins.