Protein oocytes

Stitzel ML, Pellettieri J, Seydoux G. 2006. The C. elegans DYRK Kinase MBK-2 Marks Oocyte Proteins for Degradation in Response to Meiotic Maturation. Curr Biol 16(l) 56-62. 

Westmark CJ, Ghose R, Huber PW. 2002. Phosphorylation of Xenopus transcription factor inA by an oocyte protein kinase CK2. Biochem J 362(Pt 2) 375-382. 

X /tmoles/oocyte/minute. Assuming that newly synthesized proteins are 10% leucine, the rate of protein synthesis would be 0.02 /ig/oocyte/hour (Ecker, 1972). This rate is lower than that stated earlier by a factor of about 30. By the same token, the size of the leucine pool in these experiments is 80 times smaller than the lowest value obtained from chemical determinations. Thus, the amount of free mino acids active in oocyte protein synthesis is substantially smaller than... 

Fig. 2. Calf A2 crystallin synthesis in 14 S mBNA-injected oocytes. One should note that only the basic urea gel can resolve a-ciystaUin into its four constituent polypeptide chains. Batches of oocytes were injected with 14 S RNA (isolated from calf lens epithelial tissue) and the frog cells were then incubated overnight in [ S]methionine (0.5 mCi/ml). The cells were homogenized with marker a-cryslal-lin and the supernatant proteins were analyzed on (A) SDS gels, (B) pH 3.0 urea gels, and (C) pH 8.9 urea gels, as described by Bems et td. (1972). Cel autoradiographs of newly synthesized proteins for RNA-injected and control ooc3rtes for comparison the gel staining pattern of total oocyte protein mixed with marker -crystallin is ako shown (Berns et td., 1972).

Xenobiotic induced disruption of female fertility follows essentially the same pattern as that of the male and can be caused by changes in pituitary-hypothalamic function, primary disruption of ovarian structure or hormone secretion, or changes in the rate of hormone deactivation. In addition, there may be changes in the synthesis of estrogen induced production of the yolk protein by the liver (vitellogenesis), which in turn can lead to failure to lay down sufficient yolk in the developing oocytes. Vitellogenesis provides a valuable biomarker for endocrine dysfunction in both sexes,but is more properly considered as part of the liver function. 

Cell attachment-recognition site Various proteins involved in cell-cell (eg, sperm-oocyte), virus-cell, bacterium-cell, and hormone-cell interactions... 

Observations from various systems, including yeast, suggest that phosphorylation and dephosphorylation of proteins play important roles in the mitotic and meiotic cell cycles and the differentiation of germ cells. Extracts from mitotic HeLa cells contained phosphoproteins also present in other mitotic and meiotic cell types, but not in interphase cells (Davis et al., 1983). Exposure of Xenopus oocytes to progesterone results in a burst of protein phosphorylation shortly before GVBD (Mailer et al.,... 

Other phosphatases have also been identified and may be implicated in mitotic and meiotic germ cell functions. For example, INH was originally isolated from a Xenopus oocyte cell free system as an inhibitor of pre-MPF activity (Cyert and Kirschner, 1988). INH encodes a protein phosphatase 2Athat negatively regulates MPF activity by dephosphory-lating Cdc2 on thr-161 (Lee et al., 1991 Solomon et al., 1990). 

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