1. Spatial restriction of PDK1 activation cascades by anchoring to mAKAPalpha.
- Author
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Michel JJ, Townley IK, Dodge-Kafka KL, Zhang F, Kapiloff MS, and Scott JD
- Subjects
- 3-Phosphoinositide-Dependent Protein Kinases, A Kinase Anchor Proteins, Amino Acid Sequence, Animals, Cell Line, Cloning, Molecular, Extracellular Signal-Regulated MAP Kinases genetics, Extracellular Signal-Regulated MAP Kinases metabolism, Humans, Mice, Mice, Knockout, Molecular Sequence Data, Organ Specificity genetics, RNA, Messenger genetics, Rats, Ribosomal Protein S6 Kinases, 90-kDa metabolism, Adaptor Proteins, Signal Transducing genetics, Adaptor Proteins, Signal Transducing metabolism, Alternative Splicing, Protein Serine-Threonine Kinases metabolism
- Abstract
The muscle A-kinase anchoring protein (mAKAP) tethers cAMP-dependent enzymes to perinuclear membranes of cardiomyocytes. We now demonstrate that two alternatively spliced forms of mAKAP are expressed: mAKAPalpha and mAKAPbeta. The longer form, mAKAPalpha, is preferentially expressed in the brain. mAKAPbeta is a shorter form of the anchoring protein that lacks the first 244 amino acids and is preferentially expressed in the heart. The unique amino terminus of mAKAPalpha can spatially restrict the activity of 3-phosphoinositide-dependent kinase-1 (PDK1). Biochemical and genetic analyses demonstrate that simultaneous recruitment of PDK1 and ERK onto mAKAPalpha facilitates activation and release of the downstream target p90RSK. The assembly of tissue-specific signaling complexes provides an efficient mechanism to integrate and relay lipid-mediated and mitogenic activated signals to the nucleus.
- Published
- 2005
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