An EcoRI RFLP at the human insulin-like growth factor binding protein 2 gene (IGFBP2).
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Carrier Proteins↗
Biomedical subjects
C Larsson
Publications and source records attributed to C Larsson.
Beta-casomorphins and their significance in behavioural processes.
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Amino Acid Sequence↗
Selective Inhibition of Active Uptake of Sucrose into Plasma Membrane Vesicles by Polyclonal Sera Directed against a 42 Kilodalton Plasma Membrane Polypeptide.
Several polyclonal sera were raised in rabbits and in mice against putative sucrose carrier proteins, i.e. a 42 kilodalton (O Gallet, R Lemoine, C Larsson, S Delrot [1989] Biochim Biophys Acta 978: 56-64) and a 62 kD (KG Ripp, PV Viitanen, WD Hitz, VR Fransceschi [1988] Plant Physiol 88: 1435-1445) polypeptide of the plasma membrane. The effects of these sera on the active uptake of sucrose and of valine into purified plasma membrane vesicles from sugar beet (Beta vulgaris L.) leaves and roots were studied. At a dilution of 1/50, the anti-42 kilodalton sera consistently inhibited sucrose uptake in plasma membranes from leaves or from roots. They had no effect on valine uptake. Under the same experimental conditions, the anti-62 kilodalton sera had no effect on active uptake of sucrose. The data further support the view that a 42 kilodalton polypeptide is a component of the transport system mediating sucrose uptake across the plasma membrane of plant cells.
Journal Article↗
Activation of protein kinase C in permeabilized human neuroblastoma SH-SY5Y cells.
The activation of protein kinase C was investigated in digitonin-permeabilized human neuroblastoma SH-SY5Y cells by measuring the phosphorylation of the specific protein kinase C substrate myelin basic protein4-14. The phosphorylation was inhibited by the protein kinase C inhibitory peptide PKC19-36 and was associated to a translocation of the enzyme to the membrane fractions of the SH-SY5Y cells. 1,2-Dioctanoyl-sn-glycerol had no effect on protein kinase C activity unless the calcium concentration was raised to concentrations found in stimulated cells (above 100 nM). Calcium in the absence of other activators did not stimulate protein kinase C. Phorbol 12-myristate 13-acetate was not dependent on calcium for the activation or the translocation of protein kinase C. The induced activation was sustained for 10 min, and thereafter only a small net phosphorylation of the substrate could be detected. Calcium or dioctanoylglycerol, when applied alone, only caused a minor translocation, whereas in combination a marked translocation was observed. Arachidonic acid (10 microM) enhanced protein kinase C activity in the presence of submaximal concentrations of calcium and dioctanoylglycerol. Quinacrine and p-bromophenacyl bromide did not inhibit calcium- and dioctanoylglycerol-induced protein kinase C activity at concentrations which are considered to be sufficient for phospholipase A2 inhibition.
Acetophenones↗
Characterization of prolactin receptors in human choroid plexus.
The specific binding of 125I-human prolactin (hPRL) was studied in different areas of the human brain. Particularly high binding affinity of the hormone was found in the choroid plexus and this tissue was therefore selected for further studies. The hippocampus, the hypothalamus and the pituitary were among other regions containing prolactin-binding sites. In the choroid plexus the amount of PRL receptors was significantly higher in females than in males and was also found in both sexes to decrease with age. The binding affinity of 125I-hPRL to choroid plexus was 3.0 x 10(9) M-1 and the binding capacity was 10.3 pmol per mg protein. Following solubilization with Triton X-100 the PRL receptor fraction retained its hormone-binding properties and upon molecular sieve chromatography it behaved as a protein with a molecular mass of approximately 250,000. Cross-linking of 125I-hPRL to receptors from choroid plexus and subsequent sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis indicated a major hormone-binding unit of M(r) 44,000. This value is about 7,000 smaller than that reported earlier by us for the growth hormone receptors from the same tissue, following cross-linking to 125I-human growth hormone (hGH). By affinity column chromatography a complete separation of the hPRL and hGH binding units was achieved. It was thus shown that in choroid plexus the binding sites for GH and PRL occur as discrete entities.
Aging↗
Predictive testing for multiple endocrine neoplasia type 1 using DNA polymorphisms.
Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominantly inherited predisposition to neoplastic lesions of the parathyroids, pancreas, and the pituitary. We have previously located the predisposing genetic defect to the long arm of chromosome 11 by genetic linkage. In this study, 124 members of six MEN1 families, including 59 affected individuals, were genotyped for restriction fragment length polymorphisms with different DNA probes, and the genetic linkage between these marker systems and MEN1 was determined. 13 marker systems (17 DNA probes) were found to be linked to MEN1. These markers are located within a region on chromosome 11 spanning 14% meiotic recombinations, with the MEN1 locus in the middle. Four of the marker systems are on the centromeric side of MEN1, and four on the telomeric side, based on meiotic crossovers. The remaining five DNA probes are closely linked to MEN1, with no crossovers in our set of families. The 13 marker systems can be used for an accurate and reliable premorbid test for MEN1. In most clinical situations it is possible to identify a haplotype of this part of chromosome 11 with the mutant MEN1 allele in the middle. The calculated predictive accuracy is greater than 99.5% if three such marker systems are informative. Therefore, genetic linkage testing can be used for informed genetic counseling in MEN1 families, and to avoid unnecessary biochemical screening programs.
Chromosome Mapping↗
Clinical and genetic features of adrenocortical lesions in multiple endocrine neoplasia type 1.
In multiple endocrine neoplasia type 1 (MEN-1), benign enlargement of the adrenal cortex has been found in about one third of necropsy cases. To elucidate the clinical and genetic characteristics of the MEN-1 adrenal lesion, we have investigated 33 MEN-1 patients. Twelve individuals (37%) demonstrated adrenal enlargement, which was bilateral in 7 of them. Histopathology revealed diffuse and nodular cortical hyperplasia, adenomas, and a single case of adrenocortical carcinoma. The apparently benign adrenal enlargements were not associated with presently ascertainable biochemical disturbances in the hypothalamic-pituitary-adrenocortical axis, and they were without radiological signs of progression during follow-up. The individual developing unilateral adrenocortical carcinoma showed rapid adrenal expansion, feminization, and an abnormal urinary steroid profile after 4 yr of observation for bilateral minor adrenal enlargements. Pancreatic endocrine tumors were significantly overrepresented and present in all MEN-1 individuals with adrenal involvement. In agreement with findings in sporadic cases, the MEN-1 adrenocortical carcinoma genome showed loss of constitutional heterozygosity for alleles at 17p, 13q, 11p, and 11q. The benign adrenal lesions retained heterozygosity for the MEN-1 locus at chromosome 11 q 13. Despite its prevalence and malignant potential, the pituitary-independent adrenocortical proliferation does not appear to be a primary lesion in MEN-1, but might represent a secondary phenomenon, perhaps related to the pancreatic endocrine tumor.
Adrenal Cortex↗
Morphology, DNA ploidy and allele losses on chromosome 11 in sporadic hyperparathyroidism and that associated with multiple neoplasia, type 1.
OBJECTIVE: To analyse different forms of hyperparathyroidism (for example, sporadic and multiple endocrine neoplasia type 1 (MEN 1)) by histopathology, DNA cytometry and by the presence of allele losses on chromosome 11, thereby identifying common characteristics. MATERIAL: Enlarged glands from 26 patients with hyperparathyroidism (23 sporadic and 3 MEN 1). Cytometric assessment was made of 28 glands. RESULTS: Nine patients had multiple gland disease and 15 had single gland disease (14 sporadic and 1 MEN 1). DNA cytometry showed that 18 (15 sporadic and all 3 MEN 1) were diploid, seven tetraploid, and two aneuploid. Two glands from one sporadic case showed different ploidy patterns. Seven patients with sporadic and all three with MEN 1 hyperparathyroidism had allele losses for chromosome 11 in the analysed glands. CONCLUSION: There were no significant differences in histopathological appearances, ploidy, or allele losses among abnormal glands from a variety of forms of hyperparathyroidism.
Adult↗
Sublocalization of the multiple endocrine neoplasia type 1 gene.
Tumorigenesis in multiple endocrine neoplasia type 1 (MEN 1) involves the unmasking of a recessive mutation at the MEN 1 locus which has been mapped to chromosomal region 11q11-13. By analyzing 58 DNA markers on a panel of radiation-reduced somatic cell hybrids, the region encompassing the MEN 1 gene was divided into nine subregions. Pulsed field gel electrophoresis analysis of markers within subgroups showed that the recombination rate around the MEN 1 locus is high. Combined linkage analysis in MEN 1 families and deletion mapping in MEN 1-related tumors suggest the MEN 1 gene is located centromeric to D11S807 and telomeric to PYGM.
Animals↗
Practical guidelines for DNA-based testing in multiple endocrine neoplasia type 1.
Multiple endocrine neoplasia type 1 (MEN 1) is an autosomal dominant predisposition to neoplastic lesions of the parathyroid glands, the neuroendocrine pancreas, and the anterior pituitary gland. The predisposing genetic defect was localized to the long arm of chromosome 11 by genetic linkage analysis in three affected families. By analyzing six MEN 1 families with 14 DNA marker systems located close to the MEN 1 gene, we have developed a method to identify carriers of the MEN 1 predisposition. We describe practical aspects of such DNA-based diagnostic procedures.
Blotting, Southern↗
Detailed physical map of human chromosomal region 11q12-13 shows high meiotic recombination rate around the MEN1 locus.
We have constructed a physical map of the region q12-13 on chromosome 11 by combining data generated from a panel of radiation-reduced somatic cell hybrids and pulsed-field gel electrophoresis (PFGE). Twenty different genetic markers have been sublocalized and ordered within this region and a total of 8.0 megabases has been mapped in detail using rare-cutting restriction endonucleases and PFGE. In two instances, the long-range restriction PFGE map spans the total distance between pairs of loci that have been previously mapped by genetic linkage in reference families. Comparison of this physical map with the available linkage map indicates a great variation in the recombination frequency over the region. The recombination rate is higher than expected, particularly for markers flanking the MEN1 region. Thus, for the closest pair of linked markers on the centromeric side, one centimorgan corresponds to approximately 300 kilobases, and for markers on the telomeric side, one centimorgan corresponds to approximately 350-600 kilobases.
Animals↗
Identification of an autoinhibitory domain in the C-terminal region of the plant plasma membrane H(+)-ATPase.
Proteolytic (trypsin) treatment removes a small terminal segment from the 100-kDa plant plasma membrane H(+)-ATPase. This results in activation of H+ pumping across the plasma membrane, suggesting that an inhibitory domain is located in one of the terminal regions of the enzyme (Palmgren, M.G., Larsson, C., and Sommarin, M. (1990) J. Biol. Chem. 265, 13423-13426). In order to identify the origin of the fragment released by trypsin, polyclonal antibodies were raised against the first 55 amino acids (N-terminal region), the last 99 amino acids (C-terminal region), and a portion of 150 amino acids in the central part of the enzyme as deduced from one of the H(+)-ATPase genes (PMA2) of Arabidopsis thaliana. The native, 100-kDa H(+)-ATPase was recognized by all three antisera in Western blots. By contrast, the approximately 90-kDa polypeptide appearing after trypsin treatment was only recognized by the antisera against the N-terminal and central region, but not by the antiserum against the C-terminal region, suggesting that the inhibitory domain is located in this part of the enzyme. To more closely determine the position of the inhibitory domain, three peptides representing conserved parts of the C-terminal region were synthesized (residues 861-888, 912-943, and 936-949 of the Arabidopsis (PMA2) sequence). Only one of the peptides (residues 861-888) affected H+ pumping by the trypsin-activated (approximately 90-kDa) enzyme. This peptide of 28 amino acids inhibited H+ pumping with an IC50 of about 15 microM, suggesting that the auto-inhibitory domain is located within the corresponding part of the C-terminal region.
Adenosine Triphosphate↗
Structure and localization of the human insulin-like growth factor-binding protein 2 gene.
Insulin-like growth factor binding proteins (IGFBPs) are extracellular proteins that specifically bind IGF and modulate their effects. The human IGFBP2 gene was studied and shown to be localized to chromosome 2 region q33-q34, by somatic cell hybrid analysis and in situ hybridization. Structural characterization of the gene showed that it consists of four exons with three introns of lengths 27.0, 1.0, and 1.9 kilobase-pairs. Comparison of the encoded protein sequence of each exon in IGFBP1, 2, and 3 reveals the highest amino acid identity, 28%, in exon 1, while the lowest was found in exon 2. However, pairwise sequence comparisons demonstrate 50% identity between the protein sequences encoded by exon 4 in IGFBP1 and 2, while their respective identities with IGFBP3 are only 25 and 30%.
Amino Acid Sequence↗
Identification of twelve new RFLP-markers on chromosome 22q11-qter.
We have previously identified and regionally localized 195 chromosome-22-specific DNA markers. We now report restriction fragment length polymorphisms detected by 9 phage markers mapped to 22q11-q12, two cosmid clones mapped to 22q12-q13 and one plasmid mapped to 22q13-qter. These markers may be useful tools for mapping disease genes such as the NF2 locus, on chromosome 22.
Alleles↗
Transmembrane Electron Transport in Plasma Membrane Vesicles Loaded with an NADH-Generating System or Ascorbate.
Sugar beet (Beta vulgaris L.) leaf plasma membrane vesicles were loaded with an NADH-generating system (or with ascorbate) and were tested spectrophotometrically for their ability to reduce external, membrane-impermeable electron acceptors. Either alcohol dehydrogenase plus NAD(+) or 100 millimolar ascorbate was included in the homogenization medium, and right-side-out (apoplastic side-out) plasma membrane vesicles were subsequently prepared using two-phase partitioning. Addition of ethanol to plasma membrane vesicles loaded with the NADH-generating system led to a production of NADH inside the vesicles which could be recorded at 340 nanometers. This system was able to reduce 2,6-dichlorophenolindophenol-3'-sulfonate (DCIP-sulfonate), a strongly hydrophilic electron acceptor. The reduction of DCIP-sulfonate was stimulated severalfold by the K(+) ionophore valinomycin, included to abolish membrane potential (outside negative) generated by electrogenic transmembrane electron flow. Fe(3+)-chelates, such as ferricyanide and ferric citrate, as well as cytochrome c, were not reduced by vesicles loaded with the NADH-generating system. In contrast, right-side-out plasma membrane vesicles loaded with ascorbate supported the reduction of both ferric citrate and DCIP-sulfonate, suggesting that ascorbate also may serve as electron donor for transplasma membrane electron transport. Differences in substrate specificity and inhibitor sensitivity indicate that the electrons from ascorbate and NADH were channelled to external acceptors via different electron transport chains. Transplasma membrane electron transport constituted only about 10% of total plasma membrane electron transport activity, but should still be sufficient to be of physiological significance in, e.g. reduction of Fe(3+) to Fe(2+) for uptake.
Journal Article↗
Prader-Willi syndrome in a Swedish rural county: epidemiological aspects.
The total population under 25 years of age in one rural county in Sweden was screened in an attempt to find all cases of Prader-Willi syndrome and to establish prevalence rates for the disorder. 11 clear and five suspect cases were found. For the seven- to 25-year-old age-group the prevalence was 13 per 100,000 for clear cases only, but 20 per 100,000 if borderline cases were included. There was a slight over-representation of males, but it was possible that this was a result of under-representation of females in the very young age-groups, in whom hypogonadism may be difficult to diagnose.
Adolescent↗
Genetic and clinical characteristics of multiple endocrine neoplasia type 1.
Multiple endocrine neoplasia type 1 (MEN 1) is an inherited disorder of autosomal-dominant type encompassing tumors of the parathyroid glands, anterior pituitary and endocrine pancreas. The genetic defect responsible for MEN 1 maps to the long arm of chromosome 11 (11q13). Constitutional heterozygosity for the MEN 1 region is lost in proliferating pancreatic endocrine and parathyroid tissue, which suggests that the MEN 1 gene belongs to the group of tumor suppressor genes (antioncogenes). Genetic screening by linkage analysis using RFLP markers allows selection of gene carriers with high degree of accuracy and makes it possible to concentrate the laborious biochemical screening efforts to family members at risk of developing the MEN 1 syndrome. Biochemical screening of the MEN 1 lesions in young asymptomatic individuals decreases the age at diagnosis with many years (decades) and therapeutic intervention can be instituted early. Although it still remains to be established whether early intervention will have an impact on mortality, our long-term experience with 20 MEN 1 kindreds suggests a reduced morbidity as a result of thorough biochemical screening.
Adult↗
Proteolytic activation of the plant plasma membrane H(+)-ATPase by removal of a terminal segment.
Incubation of oat root plasma membrane vesicles in the presence of ATP with trypsin or chymotrypsin increased the rate of ATP hydrolysis and ATP-dependent proton pumping by the plasma membrane H(+)-ATPase. Proton pumping was stimulated more than 200%, whereas ATP hydrolytic activity was stimulated about 30%. The Km (ATP) for both proton pumping and ATP hydrolysis was lowered from about 0.3 mM to below 0.1 mM. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of trypsin-treated plasma membranes revealed a decrease in a 100-kDa band and the appearance of a 93-kDa band. Western blot analysis using antibodies against the H(+)-ATPase showed that both of these bands represented the H(+)-ATPase and suggested that a 7-kDa segment was released. Extensive treatment with carboxypeptidase A also activated the H(+)-ATPase indicating that the 7-kDa segment originated from the C terminus.
Adenosine Triphosphate↗