Signal pathway-associated protein calmodulin

FIGURE 8.11 Multiple signal-transduction pathways initiated by calmodulin. Calmodulin bound to Ca2+ interacts and activates many enzymes, opening up a wide range of possible cellular responses. Abbreviations MAP-2, microtubule-associated protein 2 NO, nitric oxide Tau, tubulin assembly unit. 

Several examples of proteins involved in signal transduction pathways are reported to be encoded by auxin-induced mRNAs. These include the 3-subunit of a heterotrimeric G-protein (arcA) [105,106], cyclin-dependent protein kinases (cdc2s) [107-111], and calmodulin (PCM-1 and arCAM) [112,113]. Putative transcription factors are also represented in the list of auxin-induced mRNAs. Auxin-responsive cDNA clones for a G-box binding bZIP transcription factor (SGBF-1) [114] and a homeobox transcription factor (Athb-8) have been reported [115]. Another auxin-responsive mRNA, dbp, was proposed to be a lysine-rich nuclear protein similar to HI histone, and the recombinant protein was shown to bind nonspecilically to DNA [116]. The amino acid sequence of dbp is, however, highly similar (i.e., 67% identity and 80% similarity) to a potato plasma membrane-associated protein called remorin [117]. The remorin protein binds to both simple and complex galacturonides as well as DNA, but is not a nuclear protein in potato... 

In primary cultures of neonatal cerebellar granule neurons, all Ca2+ sensors, calmodulin, protein kinases C (PKC), and the p21(ras)/phosphatidylinositol 3 -kinase (Ptdlns-3K)/Akt pathway, converge towards NF-kB at the levels of nuclear translocation as well as transcription. The duration of NF-kB activation is a critical determinant for sensitivity toward excitotoxic stress and is dependent on the different upstream and downstream signaling associated with various kinases. This is in contrast to studies in non-neuronal cells, which either do not respond to Ca2+ or do not simultaneously activate all three cascades (Lilienbaum and Israel, 2003). Collective evidence suggests that brain inflammatory processes differ from systemic inflammation not only in the involvement of various types of neural cells but also in differences in response to second messengers. 

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