Ubiquitin, a small protein consisting of 76 amino acids, has been found in all eukaryotic cells studied. It is one of the most conserved proteins known. Two classes of ubiquitin genes are recognized. Class I is a polyubiquitin gene encoding a polyprotein of tandemly repeated ubiquitins. The class II genes are fusion products between a single ubiquitin gene and 1 of 2 other possible sequences, either 52 or 76 to 80 predominantly basic amino acids. Ubiquitin is required for ATP-dependent, nonlysosomal intracellular protein degradation, which eliminates most intracellular defective problems as well as normal proteins with a rapid turnover. Degradation involves covalent binding of ubiquitin to the protein to be degraded, through isopeptide bonds from the C-terminal glycine residue to the epsilon-amino groups of lysyl side chains. Presumably, the function of ubiquitin is to label the protein for disposal by intracellular proteases. The most abundant ubiquitin-protein conjugate, however, is ubiquitin-H2A, in which ubiquitin is bound to lys119 in histone H2A, this conjugate is not degraded. Since such ubiquitinated histones are present primarily in actively transcribed chromosomal regions, ubiquitin may play a role in regulation of gene expression. Applications: Suitable for use in ELISA. Western Blot, though not tested, may potentially be used as an application. Other applications not tested. Recommended Dilution: ELISA: 0.5-1ug/ml Western Blot: 1:1000-1:5000, Using ECL technique. See U0999-05A for positive control. Optimal dilutions to be determined by the researcher. Storage and Stability: May be stored at 4C for short-term only. For long-term storage, store at -20C. Aliquots are stable for at least 12 months at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.
