Protein kinase Mζ
|Protein kinase C, zeta|
|External IDs||Template:OMIM5 Template:MGI|
|RNA expression pattern|
|File:PBB GE PRKCZ 202178 at tn.png|
|Template:GNF Ortholog box|
Protein kinase Mζ (also called PKMζ or PKMzeta) is the independent catalytic domain of protein kinase Cζ and, lacking an autoinhibitory regulatory domain of the full-length PKCζ, is constitutively active. This constitutive or autonomous activity allows the kinase to be independent of second messengers and thus persistently active. It was originally thought of as being a cleavage product of full-length PKCζ, an atypical isoform of protein kinase C (PKC). Like other PKC isoforms, PKCζ is a serine/threonine kinase that adds phosphate groups to target proteins. It is atypical in that unlike other PKC isoforms, PKCζ does not require calcium or diacylglycerol (DAG) to become active, but rather relies on a second messenger other than DAG, presumably generated through a phosphoinositide 3-kinase (PI3-kinase) pathway. It is now known that PKMζ is not the result of cleavage of full-length PKCζ, but rather, in mammalian brain, is translated from its own brain-specific mRNA, that is transcribed from the full-length PKCζ gene. The promotor for full-length PKCζ is largely inactive in the forebrain and so PKMζ is the dominant form of ζ in the forebrain and the only PKM that is translated from its own mRNA.
PKMζ is thought to be responsible for maintaining the late phase of long-term potentiation. This theory arose from the observation that PKMζ perfused postsynaptically into neurons causes synaptic potentiation and selective inhibitors of PKMζ, when bath applied 1 hr after tetanization, inhibit the late phase or maintenance of LTP. Thus PKMζ is both necessary and sufficient for maintaining LTP. Subsequent work showed that inhibiting the kinase reversed LTP maintenance when applied up to 5 hours after LTP was induced in hippocampal slices, and after 22 hr in vivo. Inhibiting PKMζ in behaving animals erased spatial long-term memories in the hippocampus that were up to 1 month-old, without affecting spatial short-term memories. In the neocortex, thought to be the site of storage for most long-term memories, PKMζ inhibition erased memories for conditioned taste aversion in the insular cortex. PKMζ is thus the first molecule shown to be a component of the storage mechanism of long-term memory.
- Hernandez AI, Blace N, Crary JF, Serrano PA, Leitges M, Libien JM, Weinstein G, Tcherapanov A, Sacktor TC. (2003). "Protein kinase M zeta synthesis from a brain mRNA encoding an independent protein kinase C zeta catalytic domain. Implications for the molecular mechanism of memory". J. Biol. Chem. 278 (41): 40305–16. PMID 12857744.
- Ling D, Benardo L, Serrano P, Blace N, Kelly M, Crary J, Sacktor T (2002). "Protein kinase Mzeta is necessary and sufficient for LTP maintenance". Nat. Neurosci. 5 (4): 295–6. PMID 11914719.
- Serrano P, Yao Y, Sacktor T (2005). "Persistent phosphorylation by protein kinase Mzeta maintains late-phase long-term potentiation". J Neurosci. 25 (8): 1979–84. PMID 15728837.
- Pastalkova E, Serrano P, Pinkhasova D, Wallace E, Fenton A, Sacktor T (2006). "Storage of spatial information by the maintenance mechanism of LTP". Science. 313 (5790): 1141–4. PMID 16931766.
- Shema R, Sacktor T, Dudai Y (2007). "Rapid erasure of long-term memory associations in the cortex by an inhibitor of PKMζ". Science. 317 (5840): 951–3. PMID 17702943.
- Slater SJ, Ho C, Stubbs CD (2003). "The use of fluorescent phorbol esters in studies of protein kinase C-membrane interactions". Chem. Phys. Lipids. 116 (1–2): 75–91. PMID 12093536.
- Carter CA, Kane CJ (2005). "Therapeutic potential of natural compounds that regulate the activity of protein kinase C.". Curr. Med. Chem. 11 (21): 2883–902. PMID 15544481.