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Expression level of adenosine kinase in rat tissues. Lack of phosphate effect on the enzyme activity.

100%

Sakowicz M., Grdeń M., Pawełczyk T.

2001

vol. 48

issue 3

745-754

In this report we describe cloning and expression of rat adenosine kinase (AK) in Esccherichaia coli cells as a fusion protein with 6xHis. The recombinant protein was purified and polyclonal antibodies to AK were generated in rabbits. Immunoblot analysis of extracts obtained from various rat tissues revealed two protein bands reactive with anti-AK IgG. The apparent molecular mass of these bands was 48 and 38 kDa in rat kidney, liver, spleen, brain, and lung. In heart and muscle the proteins that react with AK antibodies have the molecular masses of 48 and 40.5 kDa. In order to assess the relative AK mRNA level in rat tissues we used the multiplex PCR technique with β-actin mRNA as a reference. We found the highest level of AK mRNA in the liver, which decreased in the order kidney >spleen >lung >heart >brain >muscle. Measurement of AK activity in cytosolic fractions of rat tissues showed the highest activity in the liver (0.58 U/g), which decreased in the order kidney >spleen >lung >brain >heart >skeletal muscle. Kinetic studies on recombinant AK as well as on AK in the cytosolic fraction of various rat tissues showed that this enzyme is not affected by phosphate ions. The data presented indicate that in the rat tissues investigated at least two isoforms of adenosine kinase are expressed, and that the expression of the AK gene appears to have some degree of tissue specificity.

Expression level of Ubc9 protein in rat tissues.

88%

Gołębiowski F., Szulc A., Sakowicz M., Szutowicz A., Pawełczyk T.

2003

vol. 50

issue 4

1064-1073

Ubc9 is a homologue of the E2 ubiquitin conjugating enzyme and participates in the covalent linking of SUMO-1 molecule to the target protein. In this report we describe a simple and efficient method for obtaining pure human recombinant Ubc9 protein. The purified Ubc9 retained its native structure and was fully active in an in vitro sumoylation assay with the promyelocytic leukaemia (PML) peptide as a substrate. In order to better understand the physiology of Ubc9 protein we examined its levels in several rat tissues. Immunoblot analyses performed on tissue extracts revealed quantitative and qualitative differences in the expression pattern of Ubc9. The Ubc9 protein was present at a high level in spleen and lung. Moderate level of Ubc9 was detected in kidney and liver. Low amount of Ubc9 was observed in brain, whereas the 18 kDa band of Ubc9 was barely visible or absent in heart and skeletal muscle. In heart and muscle extracts the Ubc9 antibodies recognized a 38 kDa protein band. This band was not visible in extracts of other rat tissues. A comparison of the relative levels of Ubc9 mRNA and protein indicated that the overall expression level of Ubc9 was the highest in spleen and lung. In spleen, lung, kidney, brain, liver and heart there was a good correlation between the 18 kDa protein and Ubc9 mRNA levels. In skeletal muscle the Ubc9 mRNA level was unproportionally high comparing to the level of the 18 kDa protein. The presented data indicate that in the rat the expression of the Ubc9 protein appears to have some degree of tissue specificity.

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2 Acta Biochimica Polonica

1 2003

1 2001

2 Pawełczyk T.

2 Sakowicz M.

1 Gołębiowski F.

1 Grdeń M.

1 Szulc A.

1 Szutowicz A.

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Expression level of adenosine kinase in rat tissues. Lack of phosphate effect on the enzyme activity.

Expression level of Ubc9 protein in rat tissues.