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H Ponstingl

Publications and source records attributed to H Ponstingl.

At least 55 records · Page 3Linked to original sources
PubMed1986

Cytokeratin expression in simple epithelia. I. Identification of mRNA coding for human cytokeratin no. 18 by a cDNA clone.

To study the regulation of the expression of cytokeratins characteristic of simple epithelia, i.e., human cytokeratins nos. 7, 8, 18, and 19, we prepared several cDNA clones coding for these proteins and their bovine counterparts. In the present study, we describe a cDNA clone of the mRNA coding for human cytokeratin no. 18, which was isolated from an expression library using the monoclonal antibody, KG 8.13. This clone (756 nucleotides, excluding the polyA portion), encodes approximately one-half of the mRNA (approximately 1.4 kb), identifies one mRNA band in Northern-hybridization blots, and specifically selects one mRNA species coding for cytokeratin no. 18, as demonstrated by translation in vitro. Comparison of the deduced amino acid sequence--confirmed by direct amino-acid-sequence analyses of some polypeptide fragments produced by cleavage with cyanogen bromide--indicated that cytokeratin no. 18 is a member of the acidic (type I) subfamily of cytokeratins. It has only limited sequence homologies in common with other intermediate-sized filament proteins, and these are essentially restricted to certain domains of the alpha-helical rod portion. The carboxyterminal tail sequence does not contain glycine-rich elements, thus distinguishing this cytokeratin from those acidic (type I) cytokeratins that are characterized by this feature. The similarities and differences between cytokeratin no. 18 and previously described epidermal cytokeratins are discussed in relation to the differences in the stability of the complexes which this cytokeratin forms with basic (type II) cytokeratins, as well as in relation to possible functional differences of cytokeratins in simple and stratified epithelia.

Amino Acid Sequence↗
PubMed1985

DNA intercalators induce specific release of HMG 14, HMG 17 and other DNA-binding proteins from chicken erythrocyte chromatin.

Chicken erythrocyte nuclei were incubated with DNA intercalating agents in order to isolate from chromatin specific DNA-binding proteins whose binding specificity may be determined by DNA secondary and/or tertiary structure. The intercalating agents ethidium bromide (EtBr) and propidium iodide induce the specific release of high mobility group proteins HMG 14 and HMG 17 under low ionic strength conditions. Chloroquine (CQ) intercalation also results in the selective liberation of HMG 14 and HMG 17, but, in addition, selectively releases other nuclear proteins (including histone H1A) in a pH- and ionic strength-dependent fashion. The use of this new 'elutive intercalation' technique for the isolation and purification of 'sequence-specific' and 'helix-specific' DNA-binding proteins is suggested.

Animals↗
PubMed1985

Biochemical characterization of desmosomal proteins isolated from bovine muzzle epidermis: amino acid and carbohydrate composition.

The seven major desmosomal polypeptides from isolated bovine muzzle desmosomes ranging from Mr 75 000 to 250 000 were separated by gel electrophoresis, isolated and characterized with respect to their amino acid composition and sugar content. The two largest polypeptides (bands 1 and 2), i.e. desmoplakins I and II, are similar in their amino acid composition, confirming our previous immunological and biochemical data, and display a relatively high glycine content. In contrast, the other two cytoplasmic components also believed to be associated with the desmosomal plaque, i.e. polypeptides of bands 5 (Mr 83 000) and 6 (Mr 75 000), differ significantly in their amino acid composition from the desmoplakins and from each other. All four candidate polypeptides for plaque association, i.e. bands 1, 2, 5, and 6, show no significant glycosylation. The glycoproteins 4a and 4b (Mr 115 000 and 130 000) are similar in their amino acid composition, peptide analysis and immunological reactivity. Both are relatively rich in mannose and galactose but also contain sialic acid. Our determinations also indicate that the two polypeptides differ significantly in their N-acetylglucosamine and mannose content. Most, if not all, of the sugar residues are associated with a water-soluble fragment of Mr 15 500 obtained after limited digestion with V8 protease. The glycopolypeptides obtained in band 3 (Mr 164 000-175 000) are distinct from the glycopolypeptides 4a and 4b in amino acid composition, sugar content, isoelectric pH values, certain antigenic determinants and in their pattern of cleavage products obtained by treatment with proteases or cyanogen bromide. The results identify polypeptides of bands 3, 4a and 4b as glycosylated with characteristic sugar compositions. It is suggested that the major glycoproteins (bands 3, 4a, 4b) of the desmosome are integral membrane components arranged in a special way conferring resistance to detergent treatment. The possible roles of these glycoproteins in cell recognition and in adhesive functions of the desmosome are discussed.

Amino Acids↗
PubMed1983

Tubulin amino acid sequence and consequences.

The 451 residues of alpha-tubulin from pig brain and the 445 residues of the beta-subunit display 41% sequence identity. Although the primary structure is highly conserved during evolution, several positions in each of the chains are heterogeneous, indicating four alpha-variants and two of the beta-polypeptide. Both C-terminal parts are highly acidic. Small regions can be correlated to sequences of nucleotide binding proteins. Cysteine beta 201 may be involved in the colchicine binding site.

Amino Acid Sequence↗
PubMed1981

Tubulin sequence conservation.

Various aspects of the primary structure of tubulin are discussed and tubulin sequence data are compared. A hypothesis concerning the evolution of tubulin is also presented. The main points raised are: (1) Identical glycyl rich regions in alpha- and beta-tubulin, which are similar in both sequence and predicted secondary structure to a region in several nucleotide binding enzymes, may be involved in binding GTP. (2) Small regions of homology are present to actin, myosin and troponin T. These homologous regions may have the same function, resulting in a convergence of their sequences, or they may have arisen by a pathway of protein evolution which is still only very poorly understood. (3) The mutation rate between pig and chick brain tubulin is 0.22 PAMs (accepted point mutations/100 residues) per hundred million years, which is comparable to that of the histones. At an early time in its history, however, the tubulin heterodimer appears to have had a relatively high rate of mutation. This may have been during the evolution of the first eukaryotes.

Amino Acid Sequence↗
PubMed1981

Complete amino acid sequence of alpha-tubulin from porcine brain.

The amino acid sequence of alpha-tubulin from porcine brain was determined by automated and manual Edman degradation of eight sets of overlapping peptides. It comprises 450 residues plus a COOH-terminal tyrosine that is present only in 15% of the material. A region of 40 residues at the COOH-terminus is highly acidic, mainly due to 16 glutamyl residues. This high concentration of negative charge suggests a region for binding cations. At least six positions, most of them around position 270, are occupied by two amino acid residues each. Several of these exchange sites were assigned to specific peptides by analysis of the purified corresponding fragments. These data indicate four alpha-tubulins in porcine brain. Although alpha-tubulin on the whole is unrelated to other proteins, there are regions that can be correlated to sequences of the myosin head, to actin, to tropomyosin, and to troponins C and T.

Animals↗
PubMed1981

Complete amino acid sequence of beta-tubulin from porcine brain.

The primary structure of porcine brain beta-tubulin was determined by automated and manual Edman degradation of six sets of overlapping peptides. The protein consists of 445 amino acid residues and has a minimum of six positions that are heterogeneous, indicating at least two beta-tubulins in porcine brain. Comparison of the optimally aligned sequences of alpha-tubulin and beta-tubulin indicates that 41% of their primary structures are identical. A region rich in glycyl residues is similar both in sequence and predicted secondary structure to the phosphate binding loop of several nucleotide binding enzymes. beta-Tubulin contains a highly acidic COOH-terminal region that resembles the NH2-terminus of troponin T.

Amino Acid Sequence↗
PubMed1978

Amino acid sequence of progesterone-induced rabbit uteroglobin.

Uteroglobin, a steroid-binding protein of the uterine secretion of the rabbit which is induced by progesterone, comprises two identical polypeptide chains of 70 amino acid residues linked by two disulfide bonds. The primary structure has been determined by using both automated and manual methods of Edman degradation. Overlapping peptides were isolated from tryptic, and CNBr digests. The sequence is not homologous to any known protein except for a small acidic region (residues 22-29) resembling a sequence found in somatotropin. The C-terminal half is relatively basic. Implications for the secondary structure are discussed.

Amino Acid Sequence↗
PubMed1976

[Rule of antibody structure. The primary structure of a monoclonal IgG1 immunoglobulin (myeloma protein Nie), II: isolation and amino acid sequence of the tyrptic peptides from the H-chain (author's transl)].

The reduced and carboxymethylated H-chain of protein Nie was digested with trypsin. 40 tryptic peptides were isolated from the digest by ion exchange chromatography, accounting for the entire amino acid composition of the polypeptide chain. Sequence studies performed with these fragments revealed the position of 444 out of 448 residues. In addition 8 overlapping cleavage products were purified which contributed to the ordering of tryptic peptides in the chain.

Amino Acid Sequence↗
PubMed1976

[The rule of antibody structure. The primary structure of a monoclonal IgG1 immunoglobulin (myeloma protein Nie). III. The chymotryptic peptides of the H-chain, alignment of the tryptic peptides and discussion of the complete structure].

In this final paper the complete primary structure of the H-chain of immunoglobulin Nie (IgG1, Gm1+, 17+) is established by overlapping tryptic fragments with chymotryptic peptides. The preceding papers dealt with the purification of the protein, the characterization of the light and heavy chains, the purification and characterization of the cyanogen bromide cleavage products, the location of the disulfide bonds, the isolation of the tryptic peptides and their sequence determination. The gamma1-chain Nie comprises 448 amino acid residues. When the protein is compared with other H-chains, the switch from the variable to the constant part occurs at position 119/120. Based on the amino acid sequence of the variable part, protein Nie belongs to subgroup III of the H-chains. It was the first protein of this subgroup to be sequenced. In the meantime several other proteins are known which have been assigned to the same subgroup on the basis of linked amino acid exchanges in comparison to members of other subgroups. This confirms the evolutionary origin of antibody variability and hence the genetically fixed antibody specific. Furthermore protein Nie is the first completely determined chain with the genetic factors Gm1+, 17+. These factors are inherited codominantly and are localized on the constant part of the gamma1-chain. By comparison with protein Eu, which is Gml-, 4+ and therefore an allele of Nie, these serologically defined factors are correlated with Eu. Besides the amino acid exchanges caused by the Gm-factors we elucidated a series of differences to the constant part of the protein Eu. These differences include 6 amide postions and the sequence from residues 387 to 391. Using the structure of IgG1 Nie as an example some rules for the evolution of immunoglobulin sequences have been described. In particular the "elongation-rule" and the "Disulfide-rule" are discussed. While chain-elongation of the H-chains can simply be explained by repeated gene duplications of a basic unit containing ca 110 amino acids, the location of disulfide bonds is determined partly by gene duplication, which implies multiplication of evolutionary "old" cystein residues and partly by the relatively recent acquisition of "new" cystein in appropriate sites. Most evident is the origin of the "hindge-region" by partial gene duplication on the C-terminal residues of the first homology region.

Amino Acid Sequence↗