Resolution of phosphoglucomatase and the 62-kDA acceptor for the glucosylphosphotransferase

Journal Article · Sun Jul 01 04:00:00 EDT 1990 · Archives of Biochemistry and Biophysics; (USA)

DOI:https://doi.org/10.1016/0003-9861(90)90526-5· OSTI ID:6708959

Marchase, R B; Richardson, K L; Srisomsap, C; Drake, R R; Haley, B E ^[1]

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1. Univ. of Alabama, Birmingham (USA)

The radioactive, photoactivatable labeling probe (beta-32P)5-azidouridine 5'-diphosphoglucose has recently been shown to label a 62-kDa protein in crude homogenates and in partially purified enzyme preparations without photoactivation. Here, we report that a portion of this radioactivity is due to labeling of phosphoglucomutase by contaminating levels of (32P)alpha Glc-1-P initially present at less than 1% of the total 32P. This conclusion is based in part on the ability of excess unlabeled alpha Glc-1-P and Glc-6-P, but not UDP-Glc, to block the labeling. In addition, the labeled protein in liver homogenates had a tryptic peptide pattern similar to that of authentic phosphoglucomutase. These findings, however, raised a second question. Assays for the UDP-Glc: glycoprotein glucosyl phosphotransferase (Glc phosphotransferase) have utilized (beta-32P)UDP-Glc and have resulted in the labeling of a small number of acceptors, including one of approximately 62 kDa. Despite the fact that these assays had routinely been performed in the presence of 1 mM alpha Glc-1-P, the coincidence in molecular weights led to these further studies. We conclude that the acceptor of approximately 62 kDa is distinct from phosphoglucomutase. This conclusion is based on differences in the time courses of incorporation, the specificity of blocking agents, the presence of covalently linked glucose, the products of acid hydrolysis and of beta-elimination, and isoelectric points.

• OSTI ID: 6708959
• Journal Information: Archives of Biochemistry and Biophysics; (USA), Journal Name: Archives of Biochemistry and Biophysics; (USA) Vol. 280:1; ISSN ABBIA; ISSN 0003-9861
• Country of Publication: United States
• Language: English

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550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AFFINITY
ALDEHYDES
AMINO ACID SEQUENCE
ANIMALS
AZINES
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BODY
CARBOHYDRATES
DAYS LIVING RADIOISOTOPES
DIGESTIVE SYSTEM
ENZYMES
GLANDS
GLUCOSE
HETEROCYCLIC COMPOUNDS
HEXOSES
HYDROLASES
HYDROXY COMPOUNDS
ISOTOPE APPLICATIONS
ISOTOPES
LABELLING
LIGHT NUCLEI
LIVER
MAMMALS
MOLECULAR STRUCTURE
MOLECULAR WEIGHT
MONOSACCHARIDES
NUCLEI
NUCLEOSIDES
NUCLEOTIDES
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
PEPTIDE HYDROLASES
PHOSPHORUS 32
PHOSPHORUS ISOTOPES
PHOSPHORUS-GROUP TRANSFERASES
PHOSPHOTRANSFERASES
PYRIMIDINES
RADIOISOTOPES
RATS
RIBOSIDES
RODENTS
SACCHARIDES
SERINE PROTEINASES
TRACER TECHNIQUES
TRANSFERASES
TRYPSIN
URACILS
URIDINE
VERTEBRATES