Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0016632 (Fox)
 1,461 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A complex of orotate phosphoribosyltransferase and orotidylate decarboxylase has been shown to exist in three molecular weight forms (Brown, G. K., Fox, R. M., and O'Sullivan, W. J. (1975), J. Biol. Chem. 250, 7352). The smallest of these, of molecular weight 62 000, was subjected to further study. On the basis of the inactivation of the enzyme activities, carried out in the presence of low concentrations of guanidine hydrochloride, and of changes in molecular weight of preparations during aging, it was inferred that the enzyme complex contained more than one type of subunit. This was confirmed by chromatography on Sephadex G-75 after preincubation in guanidine hydrochloride or with guanidine hydrochloride in the elution buffer. It was concluded that the enzyme complex consisted of two types of subunits, two decarboxylase units of molecular weight approximately 20 000 and two further subunits of approximately 13 000. The subunits could be separated and reassociated with partial recovery of both activities. A 40 000 molecular weight form had full decarboxylase activity but no phosphoribosyltransferase activity. Restoration of the 62 000 molecular weight form resulted in restoration of both enzymatic activities. An intermediate species of molecular weight 50 000 representing a combination of the decarboxylase dimer with one of the 13 000 subunits was also demonstrated. This form required the presence of dithiothreitol in order to manifest phosphoribosyltransferase activity. A model of the system has been proposed that accounts for both the different molecular weight forms and also for the deficiency of both activities in the rare inborn error of metabolism, hereditary orotic aciduria.
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PMID:Subunit structure of the orotate phosphoribosyltransferase--orotidylate decarboxylase complex from human erythrocytes. 88 98

The collagenase domain of bovine glomerular basement membrane was isolated in soluble form after limited digestion with pepsin. Gel filtration chromatography of the domain under denaturing conditions revealed that most of the polypeptide constituents exhibit apparent molecular weights greater than the type I collagen beta-chain, while approximately 15% are similar in size to that of alpha-chain. Carboxymethyl cellulose chromatography of the alpha-size region revealed that 70% of the protein was polypeptide XIV, as previously designated (West, T. W., Fox, J. W., Jodlowski, M., Freytag, J. W., and Hudson, B. G. (1980) J. Biol. Chem. 255, 10451-10459). This polypeptide exhibits an apparent molecular weight of 102,000 as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. An absolute molecular weight value of 86,000 was determined by sedimentation equilibrium ultracentrifugation in 6 M guanidine hydrochloride. About 15% of the mass is carbohydrate which exists in the form of glucosylgalactosylhydroxylysine. Thus, the polypeptide backbone has a molecular weight of 73,000, a value which is considerably smaller than the alpha-chains of classical collagen. The amino acid and carbohydrate composition and cyanogen bromide patterns indicate that polypeptide XIV has a structure similar to that of C-chain or alpha 1 (IV) collagen which has been identified in other tissues. In addition, the cyanogen bromide pattern of the entire collagenous domain is similar to that of polypeptide XIV, suggesting that the latter is a structural segment of many of the higher molecular weight components.
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PMID:Bovine glomerular basement membrane. Characterization of an alpha-size collagenous polypeptide. 725 9