Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P50583 (asymmetrical)
 12,197 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The generation of egg-laying behavior in the marine mollusk Aplysia involves a prolonged burst discharge in the neuroendocrine bag cells, which secrete neuropeptides derived from the egg-laying hormone/bag cell peptide (ELH/BCP) precursor protein. 2. Besides the bag cells, which are located in the abdominal ganglion, small clusters of neurons in the cerebral and pleural ganglia also express the ELH/BCP neuropeptides. We made intracellular recordings from 32 of these ELH/BCP cells in right pleural ganglia, in 18 preparations, to characterize their physiological properties and their functional relationship to the bag cells. 3. The identification of these ELH/BCP cells was confirmed by pressure injection of Lucifer yellow and subsequent immunocytochemical processing for alpha-BCP immunoreactivity. 4. The basic electrophysiological properties of the pleural ELH/BCP cells were similar to those of the bag cells. These pleural cells were directly demonstrated to be electrically coupled, and direct intracellular stimulation of individual pleural ELH/BCP cells initiated prolonged, synchronous burst discharges in the entire cluster through a positive feedback mechanism. 5. Burst discharges elicited in the pleural ELH/BCP cells consistently initiated burst discharges in the bag cells. Bag cell burst discharges were less effective in initiating burst discharges in the pleural ELH/BCP cells, indicating that there were reciprocal but asymmetrical connections. 6. The results show that the pleural ELH/BCP cells are functionally coupled to the bag cells. They support the hypothesis that the pleural ELH/BCP cells are part of the descending pathway that initiates bag cell activity and egg-laying behavior, in vivo.
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PMID:Neuroendocrine bag cells of Aplysia are activated by bag cell peptide-containing neurons in the pleural ganglion. 274 15

Human apolipoprotein B100 cDNA is 14 kilobases in length and encodes a 4563-amino acid precursor protein. The corresponding human gene has been isolated as a series of overlapping lambda clones and extends over 43 kilobases. The gene comprises 29 exons and 28 introns. The distribution of introns is extremely asymmetrical, most of them appearing in the 5'-terminal one-third of the gene. Although most of the exons fall within the normal size limits for mammalian genes, two are unusually long: 1906 and 7572 base pairs. The latter exon is by far the longest reported for a vertebrate gene.
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PMID:Structure of the human apolipoprotein B gene. 294 72

The cerebral cortices of macaques (ranging in age from 10 to 37 years; n = 17) were analyzed by immunocytochemistry and electron microscopy to determine the cellular and subcellular localizations of the amyloid precursor protein and beta-amyloid protein, the cellular participants in the formation of senile plaques and parenchymal deposits of the beta-amyloid protein, and the temporal/spatial development of these lesions. Amyloid precursor protein was enriched within the cytoplasm of pyramidal and nonpyramidal neuronal cell bodies in young and old monkeys. In the neuropil, amyloid precursor protein was most abundant within dendrites and dendritic spines; few axons, axonal terminals, and resting astrocytes and microglia contained the amyloid precursor protein. At synapses, amyloid precursor protein was found predominantly within postsynaptic elements and was enriched at postsynaptic densities of asymmetrical synapses. The earliest morphological change related to senile plaque formation was an age-related abnormality in the cortical neuropil characterized by the formation of dense bodies within presynaptic terminals and dendrites and an augmented localization of the amyloid precursor protein to astrocytes and microglia. In most monkeys > 26 years of age, the neocortical parenchyma exhibited neuritic pathology and plaques characterized by swollen cytoplasmic processes, interspersed somata of neurons, and reactive glia within or at the periphery of senile plaques. Neurites and reactive astrocytes and microglia within these plaques were enriched with the amyloid precursor protein. In diffuse plaques, nonfibrillar beta-amyloid protein immunoreactivity was visualized within cytoplasmic lysosomes of neuronal perikarya and dendrites and the cell bodies and processes of activated astrocytes and microglia. In mature plaques, beta-amyloid protein immunoreactivity was associated with extracellular fibrils within the parenchyma; some cytoplasmic membranes of degenerating dendrites and somata as well as processes of activated glia showed diffuse intracellular beta-amyloid protein immunoreactivity. We conclude that morphological abnormalities at synapses (including changes in both pre- and postsynaptic elements) precede the accumulation of the amyloid precursor protein within neurites and activated astrocytes and microglia as well as the deposition of extracellular fibrillar beta-amyloid protein; neuronal perikarya/dendrites and reactive glia containing the amyloid precursor protein are primary sources of the beta-amyloid protein within senile plaques; and nonfibrillar beta-amyloid protein exists intracellularly within neurons and nonneuronal cells prior to the appearance of extracellular deposits of the beta-amyloid protein and the formation of beta-pleated fibrils.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Synaptic pathology and glial responses to neuronal injury precede the formation of senile plaques and amyloid deposits in the aging cerebral cortex. 799 40

PI-SceI, a double-stranded DNA endonuclease from Saccharomyces cerevisiae, is generated by protein splicing of an intein, which is an internal polypeptide within a larger precursor protein. The enzyme initiates the mobility of the intein by cleaving at inteinless alleles of the VMA1 gene. Genetic and biochemical studies reveal that the enzyme makes numerous base-specific and phosphate backbone contacts with its 31 bp asymmetrical recognition site. This site can be divided into two regions, both of which contain nucleotides that are essential for cleavage by PI-SceI. Region I contains the PI-SceI cleavage site while Region II includes an adjacent sequence that covers two helical turns. Mutational, interference and DNA mobility shift analyses demonstrate that Region II is sufficient for high-affinity PI-SceI binding. Within this region, PI-SceI uses primarily phosphate backbone and some major groove interactions to contact the DNA, while within Region I, protein binding involves predominantly major groove interactions that overlap and lie proximal to the cleavage site. Interestingly, DNA binding by PI-SceI induces DNA conformational changes within Region II that are entirely exclusive of Region I sequences. Furthermore, additional distortion occurs when PI-SceI binds to Region I in conjunction with Region II. The importance of this latter distortion in the cleavage pathway is underscored by substrate mutations at or near the cleavage site that reduce or eliminate both Region I DNA bending and substrate cleavage. Based on these findings, we propose a model in which sequence-specific contacts made by PI-SceI contribute to its localization to the cleavage site and to its stabilization of a DNA conformation that is required for catalysis. Finally, we discuss how the recognition characteristics of PI-SceI may have allowed the evolution of other endonucleases with altered, but similar, specificities.
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PMID:Substrate recognition and induced DNA distortion by the PI-SceI endonuclease, an enzyme generated by protein splicing. 891 99