PubMed Health⌕ Search

Biomedical subjects

H Ronne

Publications and source records attributed to H Ronne.

50 records · Page 3Linked to original sources
PubMed1985

Intron sequences reveal evolutionary relationships among major histocompatibility complex class I genes.

The multigene family of the class I histocompatibility antigens is unusual in that allelic and intergenic differences often are of equal magnitude. It has been suggested that this is due to gene conversion events, which would produce allelic variation but at the same time reduce intergenic differences. We compared the sequences of 11 class I genes in an attempt to elucidate the evolutionary history of this gene family. Our analysis shows that the intron sequences can be used to establish the order of divergence of various class I genes from each other. The results obtained agree with the order of divergence deduced from major insertion and deletion events. It appears that certain genes in the murine TL antigen-encoding region diverged very early from the H-2 and Qa-2,3 genes. The latter can be subgrouped as H-2 and Qa-2,3 genes by both sequence homology and insertion patterns. In contrast to the introns, exon sequences provide less information on evolutionary relationships. Thus, these analyses are consistent with the view that concerted evolution due to gene conversion occurs preferentially in exons.

Animals↗
PubMed1984

Sequence of an epidermal growth factor-binding protein.

A cDNA clone has been isolated that corresponds to the entire translated region of the mRNA coding for the epidermal growth factor-binding protein type B. The complete nucleotide sequence and the predicted amino acid sequence of the protein were elucidated. The protein sequence was compared to some related serine proteases. This comparison supports the notion that several serine proteases suggested to be involved in the processing of precursors to polypeptide hormones and growth factors are closely related to each other. It appears that these proteases are descendants of a common ancestral gene and thus form a distinct subfamily among the serine proteases.

Amino Acid Sequence↗
PubMed1984

Amino-terminal amino acid sequence of the nonspecific phospholipid exchange protein from bovine liver.

The amino-terminal amino acid sequence of the nonspecific phospholipid exchange protein from bovine liver has been determined. The first 52 amino-terminal residues in the sequence were identified. The sequence determined failed to show statistically significant homology to any previously published protein sequence. However, a stretch of 12 amino acids at the end of the sequence displays homology to the phosphatidylcholine-specific phospholipid exchange protein.

Amino Acid Sequence↗
PubMed1984

7S Nerve growth factor alpha and gamma subunits are closely related proteins.

The polypeptide composition and partial amino acid sequence of the 7S nerve growth factor (NGF) alpha subunit have been determined. Residues in 76 unique positions corresponding to 35% of the molecule were identified. The sequence shows that the NGF alpha subunit is closely related to the NGF gamma subunit and thus a member of the same protein family as the serine proteases. This finding is unexpected since the NGF alpha subunit is devoid of detectable protease activity. However, the NGF alpha subunit differs in one important respect from the NGF gamma subunit and related serine proteases. The highly conserved amino-terminal activation cleavage structure, common to most serine proteases, has been deleted, and an uncleaved activation peptide remains attached to the amino terminus of the mature NGF alpha subunit. It is suggested that this feature is causally related to the apparent lack of proteolytic activity.

Amino Acid Sequence↗
PubMed1984

Mutations and selection in the generation of class II histocompatibility antigen polymorphism.

A comparison of seven human DR and DC class II histocompatibility antigen beta-chain amino acid sequences indicates that the allelic variation is of comparable magnitude within the DR and DC beta-chain genes. Silent and replacement nucleotide substitutions in six DR and DC beta-chain sequences, as well as in seven murine class II sequences (three I-A beta and four I-A alpha alleles) were analyzed. The results suggest that the mutation rates are of a comparable magnitude in the nucleotide sequences encoding the first and second external domains of the class II molecules. Nevertheless, the allelic amino acid replacements are predominantly located in the first domains. We conclude that a conservative selective pressure acts on the second domains, whereas in many positions in the first domains replacement substitutions are selectively neutral or maybe even favoured. Thus, the difference between the first and second domains as regards the number of amino acid replacements is mainly due to selection.

Amino Acid Sequence↗
PubMed1983

Growth factor-binding proteases in the murine submaxillary gland: isolation of a cDNA clone.

The submaxillary gland of the adult male mouse contains a number of serine proteases, several of which are involved in the proteolytic processing of precursors to growth factors and other biologically active polypeptides. Here we report the isolation and identification of a cDNA clone corresponding to one of the proteases, the type B of the epidermal growth factor-binding protein. A pronounced sequence homology was found between the predicted activation peptide of this protease and the NH2-terminal extension of the nerve growth factor alpha subunit, suggesting that the latter protein has an uncleaved activation peptide attached to its NH2 terminus.

Amino Acid Sequence↗
PubMed1983

Ligand-dependent regulation of intracellular protein transport: effect of vitamin a on the secretion of the retinol-binding protein.

As a model of ligand-dependent protein secretion the biosynthesis, intracellular transport, and release of the retinol-binding protein (RBP) were studied in primary cultures of rat hepatocytes pulse-labeled with [35S]methionine. After various periods of chase RBP was isolated by immunoprecipitation and identified by SDS PAGE. Both normal and vitamin A-deficient hepatocytes synthesized RBP. The normal cells secreted the pulse-labeled RBP within 2 h. RBP synthesized by deficient cells was not secreted, and intracellular degradation of the protein appeared to be slow. Deficient cells could be induced to secrete RBP on the addition of retinol to the culture medium. This occurred also after protein synthesis had been blocked by cycloheximide. Since retinol induces the secretion of RBP, accumulated in the endoplasmic reticulum (ER), it seems reasonable to conclude that the transport of RBP from the ER to the Golgi complex is regulated by retinol.

Animals↗
PubMed1983

Structure and tissue distribution of some retinoid-binding proteins.

Vitamin A has, apart from its function in the visual pigments, general effects on several organs. Early signs of vitamin A deficiency include keratinization of epithelia and hyperkeratosis of the skin. To elucidate a generalized function for vitamin A, we have taken the approach of tracing the vitamin from its storage site in the liver via its blood transport by the retinol-binding protein (RBP) to its uptake by susceptible cells. We have also examined the intracellular occurrence of vitamin A as regards its binding to specific receptor proteins. Here we summarize data on the amino acid sequences of several vitamin A-binding proteins. The finding that CRBP and CRABP, the two intracellular proteins, are homologous to each other, to a myelin protein, and to a fatty acid-binding protein may shed light on the functions of these proteins. Retinoic acid, which binds to CRABP but not CRBP, induces differentiation of teratocarcinoma cells. This is accompanied by a lowering of the CRABP concentration, an increase of the CRBP level, and an increase in the uptake of retinol from RBP. The epidermis contains both CRBP and CRABP, and their distributions are rather similar. However, in contrast to CRBP, CRABP is most abundant in cells lining the hair follicles. CRBP occurs in greatest relative amounts in the outer layers of the epidermis. Since techniques have been developed to measure CRBP and CRABP, normal and disease-affected skin may now be explored as to quantity and cellular distribution of the retinoid-binding proteins.

Amino Acid Sequence↗
PubMed1982

Partial amino-acid sequence of the epidermal growth-factor-binding protein.

The partial amino acid sequence of the epidermal growth-factor-binding protein was determined. Residues in 108 unique positions, corresponding to 45% of the molecule, were identified. The protein is a serine protease, closely related to the nerve growth factor gamma subunit. It is suggested that the epidermal growth-factor-binding protein, like other serine protease, is synthesized as a single polypeptide chain which undergoes limited endoproteolysis. The isolated material also contained minor amounts of a second serine protease. This protease is closely related to the epidermal growth-factor-binding protein, differing from it in 7 out of the 45 amino acid positions available for comparison. The latter protease may be identical to the previously described protease A.

Amino Acid Sequence↗
PubMed1980

The retinol-binding protein.

Vitamin A is transported from its storage site in the liver to the epithelial tissues by a carrier protein, the Retinol-binding protein (RBP). In plasma RBP forms a complex with thyroxine-binding prealbumin. The present article reviews available data on the RBP system. The complete primary structure of RBP has been determined. The plasma concentration of RBP is regulated by the vitamin A status so that in vitamin A deficiency RBP molecules are not secreted from the liver. RBP molecules interact with a cell membrane receptor, probably a protein component present on epithelial cells. Vitamin A is thereby delivered to the cells. The uptake of vitamin A by the cells causes a reduction of the affinity of RBP for prealbumin. The RBP molecules which no longer are able to interact efficiently with prealbumin are excreted through the kidney glomerulus and degraded.

Amino Acid Sequence↗