Gene expression protein degradation

The major metabolic, developmental and signal responsive pathways are determined by the functionality of proteins (notably enzymes) and the amounts of particular proteins. The turnover of proteins is determined by the dichotomy of gene expression (protein synthesis) and protein degradation. The nature and regulation of these various pathways are sketched below. 

All mRNA molecules are subject to attack by RNases, and this degradation is an essential aspect of the regulation of gene expression. Proteins are not made when they are not needed, and the rate of protein synthesis is determined by... 

C. Protein degradation, which regulates protein availability and, hence, gene expression in the cell, occurs by two major mechanisms. 

Ishida N, Miyazaki K, Sakai T 2001 Circadian rhythm biochemistry from protein degradation to sleep and mating. Biochem Biophys Res Commun 286 1—5 Kloss B, Price JL, Saez L et al 1998 The Drosophila clock gene double-time encodes a protein closely related to human casein kinase lepsilon. Cell 94 97—107 Lau LF, Nathans D 1987 Expression of a set of growth-related immediate early genes in BALE/ c 3T3 cells coordinate regulation with c-fos or c-myc. Proc Natl Acad Sci USA 84 1182-1186... 

Activator proteins themselves can be boimd in regulatory networks, as shown in the example of the cyclins (chapter 14). The function of an activator protein can be regulated at the level of gene expression, degradation, or post-translational modification (e.g. protein phosphorylation). 

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