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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The production and secretion of multiple peptide hormones and tyrosine hydroxylase by the human neuroblastoma cell line NB-1 and the effects of dibutyryl cAMP (Bt2cAMP) and phorbol esters such as 12-O-tetradecanoyl-phorbol-13-acetate (TPA) on them were investigated. The presence of messenger RNAs (mRNAs) of vasoactive intestinal peptide (VIP)/peptide histidine methionine (PHM), preprotachykinin, and tyrosine hydroxylase was detectable in the cytoplasm of cultured NB-1 cells by in situ hybridization. Treatment with Bt2cAMP and TPA markedly increased the number of cells immunoreactive to VIP, PHM, neuropeptide Y, Met-enkephalin, substance P and tyrosine hydroxylase and also the contents of VIP and Met-enkephalin in the culture medium. Bt2cAMP and TPA induced morphological changes characteristic of endocrine differentiation, such as an increase in neuroendocrine granules and the development of rough endoplasmic reticulum and Golgi apparatus. The results indicated that treatment with Bt2cAMP and TPA induces the expression of multiple genes of peptide hormone and tyrosine hydroxylase and increases hormone production and secretion through morphological changes into endocrine cells.
Virchows Arch B Cell Pathol Incl Mol Pathol 1992
PMID:Detection of multiple hormones and their mRNAs in human neuroblastoma cell line NB-1 using in situ hybridization, immunocytochemistry and radioimmunoassay. 127 91

We have developed an efficient system for obtaining myeloma mutants defective in trans-acting factors required for immunoglobulin (Ig) gene expression. The system consists of a myeloma cell line designed for this purpose and an efficient method for selecting mutants from it. The cell line is X63.653 transfected with the mu gene, whose tailpiece sequence was replaced with the transmembrane sequence of human EGF receptor to hold mu on the cell surface and whose CH1 sequence was removed to prevent mu from being retained in the endoplasmic reticulum. It efficiently and stably expressed mu chains of IgM on the cell surface (mu m+) without light chains. To obtain mutants lacking mu m (mu m-) from the mu m+ cell line by selectively killing mu m+ cells, a method with ricin A-conjugated anti-mu antibody was more reliable than complement lysis mediated by anti-mu antibody. Applying the system, we obtained a variety of mu m- mutants.
Somat Cell Mol Genet 1992 Nov
PMID:Efficient selection of mu m-mutants from mu m-expressing myeloma cells by treatment with ricin A-conjugated anti-mu antibody. 128 53

The protein MEP24 was previously described as a glutathione peroxidase-like molecule specifically secreted by the mouse caput epididymidis. Recently, its binding to the head of spermatozoa was demonstrated. Here, the regulation of MEP24 expression was studied by analyzing transcriptional and translational activities in the epididymis (1) of adult mice castrated on day 60 and given various substitutive testosterone (T) treatments from day 90 and (2) of hemicastrated adult animals. In castrated mice, T treatment induced a significant rise in plasma T and 5 alpha-dihydrotestosterone (DHT) concentrations that greatly exceeded the control values. Owing to efficient regulation, however, the epididymal T and DHT levels were never higher than those of the controls. The restoration of MEP24 mRNA accumulation was complete when the epididymal DHT content returned to its normal value. However, when estimated in a cell-free system, the in vitro translatable MEP24 mRNA level never exceeded 70% of control values, even though the DHT and accumulated mRNAs were restored by 100% or more. In hemicastrates, the T content was normal on the castrated side, while the DHT content exhibited a significant decrease (47%). In this case, the MEP24 mRNA accumulation reached 88% of the normal value, but the translation rate, both in vitro and in vivo, was only about 50%. Ultrastructural studies showed that the normal rough endoplasmic reticulum organization in segment I cells is dependent upon the presence of testicular fluid in the epididymal duct lumen. Thus, this report shows that the MEP24 mRNA steady-state level is completely recovered in the presence of a normal epididymal DHT content, while restoration of the regulation of translation is just partial. This could be related to the cell organization but seems mainly dependent upon the presence of specific mRNA-associated factors which are probably under the control of androgens and/or molecules carried by the testicular fluid.
Mol Cell Endocrinol 1992 Nov
PMID:Regulation of the epididymal glutathione peroxidase-like protein in the mouse: dependence upon androgens and testicular factors. 130 85

Intracellular calcium levels are stringently regulated in all cells. The nature of this regulation is incompletely understood, but recent evidence indicates that the endoplasmic reticulum plays an important role in sequestering intracellular calcium. Using methods for isolating both calsequestrin and calreticulin, we have isolated a 58 kDa, high capacity calcium binding protein that exists in microsomes that shift their density in an oxalate-mediated density shift assay. This protein which we call CBP-58 bears similarities to the endoplasmic reticulum protein, calreticulin, in that it has a pI of 4.7 containing approximately 30% glutamate and aspartate, has a high capacity for calcium, and stains blue with the carbocyanine dye, 'Stains-all'. Peptide, amino acid, nucleotide and immunochemical analyses reveal further similarities between CBP-58 and calreticulin, but also some marked differences. Its tissue distribution suggests it is highly enriched in brain versus other tissues. We believe that CBP-58 is a calreticulin-like protein and that differences in the amino acid composition and sequences may reflect species diversity in calreticulin.
Brain Res Mol Brain Res 1992 Jan
PMID:Isolation of a calreticulin-like calcium binding protein from bovine brain. 131 7

Luminal proteins of the endoplasmic reticulum (ER) share a common carboxy-terminal tetrapeptide which is necessary and sufficient for their retention in the ER. In animal cells this retention signal is usually KDEL, whereas the yeast Kluyveromyces lactis uses the closely related sequences HDEL and DDEL. The yeast ERD2 gene has been shown to determine the capacity and specificity of the retention system, implying that it encodes a sorting receptor. This receptor is thought to retrieve escaped ER proteins from the Golgi, where a human homologue of this protein has been located. This dual function of binding and retrieval requires a receptor with highly specific binding at a specific location in the cell (Golgi but not ER). Here, a region of the ERD2 protein responsible for the specificity of ligand recognition has been identified using three independent approaches. A single amino acid residue is shown to selectively affect HDEL retention: substitution of residue 51 of the K. lactis receptor is sufficient to abolish recognition of HDEL but not DDEL, generating a novel retention phenotype.
J Mol Biol 1992 Mar 05
PMID:Changing the specificity of the sorting receptor for luminal endoplasmic reticulum proteins. 131 4

In the mouse mammary tumor virus (MMTV)-infected mouse T-lymphoma cell line W7MG1, glucocorticoid hormone regulates two aspects of MMTV gene expression: hormone stimulates MMTV gene transcription and increases the ratio of mature envelope proteins to envelope precursor protein produced. To separate these two effects and determine the mechanism by which hormone regulates the conversion of the envelope precursor Pr74 to the mature cleaved products gp52 and gp33, we constructed expression vectors in which the envelope gene is constitutively transcribed. Surprisingly, the envelope precursor protein Pr74 encoded by two independently isolated, allelic envelope genes behaved differently. Pr74-P (encoded by the ENV/P gene) was processed efficiently to the mature products gp52 and gp33, independently of the level of expression, hormonal induction of cellular genes, or the presence of other MMTV proteins. In contrast, under the same conditions, Pr74-N (encoded by the ENV/N gene) was not processed further despite being relatively stable. In sucrose gradient analyses, Pr74-P sedimented as monomers, whereas Pr74-N was found in high mol wt aggregates of heterogeneous size. Coimmunoprecipitation analysis determined that Pr74-N associated with BiP, whereas Pr74-P did not. This is indicative of improper folding of Pr74-N in the endoplasmic reticulum.(ABSTRACT TRUNCATED AT 250 WORDS)
Mol Endocrinol 1992 Mar
PMID:Two different genes coding for processable and nonprocessable forms of a viral envelope protein can account for the apparent hormonal stimulation of protein processing in W7MG1 lymphoma cells. 131 43

Histochemical and cytochemical methods induce a loss of endoplasmic reticulum (ER) membrane integrity in hepatocytes. In order to evaluate the degree of ER membrane integrity, glucose-6-phosphatase (G6P-A) was localized in light and electron microscopy using glucose-6-phosphate (G6P) and mannose-6-phosphate (M6P) as substrates. In case of ER membrane alteration, M6P diffuses inside the ER and is hydrolysed by a non-specific phosphohydrolase. G6P and M6P hydrolysis was quantified with image analysis methods. In light microscopy, the ratio of reaction of M6P hydrolysis/G6P hydrolysis gave 75% of non specific reaction. In electron microscopic study this ratio was about 30%. These results showed that enzyme localization methods in electron microscopy produced less ER membrane alteration than light microscopic methods.
Cell Mol Biol 1992 May
PMID:Loss of endoplasmic reticulum membrane integrity: an image analysis of the glucose-6-phosphatase system in human hepatocyte. 131 83

Retention of luminal endoplasmic reticulum (ER) proteins is mediated via a conserved carboxy-terminal tetrapeptide that serves as a signal for their retrieval from subsequent compartments of the secretory pathway. The signal is recognized by a receptor molecule that is believed to cycle between the Golgi apparatus and the ER. This receptor in Saccharomyces cerevisiae is encoded by the ERD2 gene, and a human cDNA homologue of the gene has been isolated. Binding of ligand by the product of this gene results in a shift of its steady-state location from Golgi to ER, suggesting that retrograde transport has been triggered. Here we report the identification of a related human protein with similar properties. This indicates that there are at least two distinct genes in humans that encode functional KDEL receptors.
J Mol Biol 1992 Aug 20
PMID:Sequence of a second human KDEL receptor. 132 62

The localization of gene expression of calreticulin, a calcium-binding protein in the endoplasmic reticulum, was examined throughout the entire brain of adult mice by in situ hybridization. Calreticulin mRNA is expressed widely and heterogeneously in discrete neurons throughout the brain, but the white matters expressed it weekly or faintly. In the olfactory bulb, the mRNA is expresses moderately in the mitral cells, but weakly in the periglomerular cells and internal granule cells. In the cerebrum, the gene is expressed intensely in the piriform cortex, but weakly in neocortex, the entorhinal cortex and the amygdaloid nuclei. In the hippocampal formation, calreticulin mRNA is expressed intensely in the CA1-CA3 regions but less intensely in the granule cells of the dentate gyrus. The caudate-putamen, thalamic and hypothalamic nuclei, and mammillary nuclei express the mRNA weakly or faintly. In the mesencephalon, pons and medulla, moderate expression of the mRNA is detected in the pontine nuclei and the locus ceruleus. Weak expression of the mRNA is detected in several discrete nuclei and zones such as the substantia nigra, the superior colliculus and the central gray. Expression signals of calreticulin mRNA are faint in the inferior olive. In the cerebellum, calreticulin mRNA is expressed moderately in the Purkinje cells whereas no significant expression is detected in the granule cells. The plexus choroideus of the lateral, third and fourth ventriculi express calreticulin mRNA intensely although no distinct expression of the mRNA is discerned in the ependyma.
Brain Res Mol Brain Res 1992 Aug
PMID:Localization of gene expression of calreticulin in the brain of adult mouse. 132 96

In mammalian cells, the signal recognition particle (SRP) receptor is required for the targeting of nascent secretory proteins to the endoplasmic reticulum (ER) membrane. We have identified the Saccharomyces cerevisiae homologue of the alpha-subunit of the SRP receptor (SR alpha) and characterized its function in vivo. S. cerevisiae SR alpha is a 69-kDa peripheral membrane protein that is 32% identical (54% chemically similar) to its mammalian homologue and, like mammalian SR alpha, is predicted to contain a GTP binding domain. Yeast cells that contain the SR alpha gene (SRP101) under control of the GAL1 promoter show impaired translocation of soluble and membrane proteins across the ER membrane after depletion of SR alpha. The degree of the translocation defect varies for different proteins. The defects are similar to those observed in SRP deficient cells. Disruption of the SRP101 gene results in an approximately sixfold reduction in the growth rate of the cells. Disruption of the gene encoding SRP RNA (SCR1) or both SCR1 and SRP101 resulted in an indistinguishable growth phenotype, indicating that SRP receptor and SRP function in the same pathway. Taken together, these results suggest that the components and the mechanism of the SRP-dependent protein targeting pathway are evolutionarily conserved yet not essential for cell growth. Surprisingly, cells that are grown for a prolonged time in the absence of SRP or SRP receptor no longer show pronounced protein translocation defects. This adaptation is a physiological process and is not due to the accumulation of a suppressor mutation. The degree of this adaptation is strain dependent.
Mol Biol Cell 1992 Aug
PMID:Signal recognition particle receptor is important for cell growth and protein secretion in Saccharomyces cerevisiae. 132 99


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