Cell cycle protein modulation signaling regulation

Because the effective mounting of immune rcspotise.s requires cell proliferation and production of. signaling agents involving DNA and protein synthesis, chemical factors that interfere with cell cycling will modulate the immune responses. This interference may occur at several steps in the immune functions. A schematic presentation of various locations where chemicals can interfere with the immune system is depicted in Fig. 1. Thi.s is a simplistic. scheme and may not cover every aspect of cither the immune system or other factors that regulate the system. 

The ankyrin repeat motif is one of the most common protein-protein interaction domains. Ankyrin repeats are modules of about 33 amino acids repeated in tandem. They are found in a large number of proteins with diverse cellular functions such as transcriptional regulators, signal transducers, cell-cycle regulators, and cytoskeletal proteins. 

PPI is a major dass of eukaryotic Ser/Thr-specific protein phosphatases that regulate diverse cellular processes such as cell cycle progression, muscle contraction, carbohydrate metabolism, protein synthesis, transcription, and neuronal signaling. Its action is modulated and regulated by assodation with subunits induding various inhibitor proteins and multiple targeting subunits of which nearly 30 proteins have now been identified (review Aggen et al., 2000). The activity of the inhibitory proteins can be controlled via phosphorylation by protein kinase A as outlined in Fig. 7.16. 

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