Protein kinase C normally has a tandem repeat of a characteristic cysteine-rich sequence in C1, the conserved region of the regulatory domain. These sequences resemble the DNA-binding zinc finger domain. For the y subspecies of rat brain protein kinase C, various deletion and point mutants in this domain were constructed, and the mutated proteins were expressed in Escherichia cofi by using the T7 expression system. Radioactive phorbol 12,13-dibutyrate binding analysis indicated that a cysteine-rich zinc-finger-like sequence was essential for protein kinase C to bind phorbol ester and that one of the two sequences was sufficient for the phorbol ester binding. Conserved region C2, another region in the regulatory domain, was apparently needed for the enzyme to require Ca2' for phorbol ester binding activity.Protein kinase C (PKC) has attracted much attention since it plays a pivotal role in signal transduction for activation of many cellular functions and for control ofcell proliferation (1, 2 The C1 region has a tandem repeat characteristic of a sequence that resembles the cysteine-rich zinc-finger motif. Such a sequence motif has been identified in many DNA binding proteins that appear to be active in transcriptional regulation (14,15). However, there is presently no indication that PKC interacts with nucleic acids, and hence no information is available as to the function of this cysteine-rich sequence. By using various deletion and point mutants of the y subspecies of rat PKC expressed in Escherichia coli, the studies described herein will show that the cysteine-rich zinc-finger-like sequence is indispensable for the binding of phorbol ester to the enzyme. MATERIALS AND METHODSConstruction of Expression Plasmids. Each mutant was constructed as shown in Fig. 1. The cDNA fragment encoding amino acids 1-373 of the 'y subspecies of rat PKC was obtained from its cDNA clone of ACKRyl (10) by digestion with Nco I and BamHI. The cohesive ends of this fragment were altered to BamHI sites by E. coli DNA polymerase I (large fragment) and BamHI linkers (8 bases). It was cloned into the BamHI site of the T7 RNA polymerase-dependent expression vector pET3c (16,17), forming an in-frame fusion product with the first 11 amino acids of the T7 gene 10 product. This plasmid, designated pTB965, could express 389 amino acid residues because of the addition of 16 residues derived from T7 and linkers. Plasmid pTB967 was constructed by insertion of a BamHI-Sau3A fragment, encoding amino acids 4868The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

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Distribution of protein kinase C in the CNS of rat is presented based on immunohistochemical analysis with monoclonal antibodies against this protein kinase. Protein kinase C-like immunoreactivity was discretely localized and associated with neurons. Most, if not all, glial cells were not significantly stained. The greatest density of the immunoreactive material was seen in the following regions: the olfactory bulb (external plexiform layer), olfactory tuberculum, anterior olfactory nucleus, cerebral cortex (layers I and IV), pyriform cortex, hippocampus (strata radiatum and oriens), amygdaloid complex (central and basolateral nuclei), cerebellar cortex (molecular layer), dorsal cochlear nucleus, nucleus spinal tract of the trigeminal nerve, and dorsal horn of the spinal cord (substantia gelatinosa). Image analysis revealed that the regional distribution of the protein kinase C-like immunoreaction generally agreed with that of phorbol ester-binding sites. Immunoreactive perikarya were found in the following areas: the cerebral cortex (layers V and VI), caudate putamen, hippocampus, thalamus, amygdaloid complex, medial and lateral geniculate nucleus, superior colliculus, cerebellar cortex, nucleus spinal tract of the trigeminal nerve, dorsal cochlear nucleus, and dorsal horn of the spinal cord. Intense protein kinase C-like immunoreactivity in the neuron was observed both in the membrane and cytoplasm of the perikarya, dendrites, axons, and axon terminals, while weak immunoreaction was seen in the nuclei but almost never in the nucleoles. A map of protein kinase C-containing neurons was constructed. Such an uneven distribution in the brain suggests that this enzyme may play roles in controlling neuronal function in the areas noted.

Background: Long-term cognitive decline in postmenopausal women is associated with aging and Alzheimer disease (AD). Estrogen replacement therapy has been reported to reduce the risk of developing AD. The distribution of estrogen receptors (ERs) in neurons overlaps that of the brain neurons known to develop AD. Estrogen increases the secretion and metabolism of amyloid precursor protein, may help synapse formation, and is reported to protect neurons from toxins. Restriction fragment length polymorphisms (RFLPs) of the ERα gene at intron 1 and exon 2 were associated with a low bone mineral density in postmenopausal women and also with AD in a Japanese population.

Feast/famine regulatory proteins comprise a diverse family of transcription factors, which have been referred to in various individual identifications, including Escherichia coli leucine-responsive regulatory protein and asparagine synthase C gene product. A full length feast/famine regulatory protein consists of the N-terminal DNA-binding domain and the C-domain, which is involved in dimerization and further assembly, thereby producing, for example, a disc or a chromatin-like cylinder. Various ligands of the size of amino acids bind at the interface between feast/famine regulatory protein dimers, thereby altering their assembly forms. Also, the combination of feast/famine regulatory protein subunits forming the same assembly is altered. In this way, a small number of feast/famine regulatory proteins are able to regulate a large number of genes in response to various environmental changes. Because feast/famine regulatory proteins are shared by archaea and eubacteria, the genome-wide regulation by feast/famine regulatory proteins is traceable back to their common ancestor, being the prototype of highly differentiated transcription regulatory mechanisms found in organisms nowadays.