Phosphorylation of tyrosine in cultured human placenta |
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Authors: | Hanan Galski Nathan De Groot Judith Ilan Abraham A. Hochberg |
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Affiliation: | 1. Department of Biological Chemistry, the Hebrew University of Jerusalem, Institute of Life Sciences, 91904 Jerusalem Israel;2. Department of Reproductive Biology, Case Western Reserve University, School of Medicine, Cleveland, OH U.S.A. |
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Abstract: | The [32P]phosphoamino acids in proteins of first-trimester and term-cultured human placentas have been separated and their relative amounts have been measured. Significant phosphorylation of tyrosine residues could be detected in the cultured placental tissue at different stages of gestation. The phosphotyrosine accounts for 2–4% of the total acid-stable phosphate in the phosphoamino acids after partial acid hydrolysis. The difference in the extent of [32P]tyrosine in various placentas seems to be a function of biological variation of the individual placentas, rather than a function of placental age and stage of gestation. In contrast, a significant difference in the phosphorylation ratio of serine and threonine could be measured between first-trimester and term placentas. As more evidence is accumulating that protein phosphorylation of tyrosine is involved in the processes of cellular growth and proliferation, our findings of the relatively high tyrosine phosphorylation in human placenta strongly suggest that this type of protein phosphorylation may play an important role in the placental growth and development. Furthermore, these findings may correlate with the existence of the endogenous RNA virus-like particles found in normal human placenta. |
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Keywords: | Tyrosine Phosphorylation Development (Human placenta) Hepes 4-(2-hydroxyethyl)-1-piperazinepropanesulfonic acid |
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