Biomedical subjects

C Ampe

Publications and source records attributed to C Ampe.

43 records · Page 3Linked to original sources

PubMed1988

The primary structure of the basic isoform of Acanthamoeba profilin.

Acanthamoeba profilin-II [Kaiser, D.A., Sato, M., Ebert, R. F. and Pollard, T.D. (1986) J. Cell. Biol. 102, 221-226] was digested with trypsin or cleaved by 2-(2-nitrophenylsulphenyl)-3-methyl-3-bromoindolenine. The tryptic peptides were purified by reversed-phase-high-performance liquid chromatography and completely sequenced using automated gas-phase sequence analysis. The complete profilin-II sequence was deduced by ordering the tryptic peptides using the sequence information of the tryptophan-cleavage products. Acanthamoeba profilin-II was found to be homologous to the previously determined profilin-I sequence [Ampe, C., Vandekerckhove, J., Brenner, L., Tobacman, L. and Korn, E.D. (1985) J. Biol. Chem. 260, 834-840]. Like profilin-I, profilin-II consists of 125 amino acids, has a blocked NH2 terminus and a trimethyllysine residue at position 103. Profilin-II differs in at least 21 positions from one of the profilin-I isoforms. The amino acid exchanges are mainly concentrated in the middle part of the sequence. Profilin-II contains two more basic residues than profilin-I, which explains its higher isoelectric point.

Acanthamoeba↗

PubMed1987

The F-actin capping proteins of Physarum polycephalum: cap42(a) is very similar, if not identical, to fragmin and is structurally and functionally very homologous to gelsolin; cap42(b) is Physarum actin.

We have carried out a primary structure analysis of the F-actin capping proteins of Physarum polycephalum. Cap42(b) was completely sequenced and was found to be identical with Physarum actin. Approximately 88% of the sequence of cap42(a) was determined. Cap42(a) and fragmin were found to be identical by amino acid composition, isoelectric point, mol. wt, elution time on reversed-phase chromatography and amino acid sequence of their tryptic peptides. The available sequence of cap42(a) is greater than 36% homologous with the NH2-terminal 42-kd domain of human gelsolin. A highly homologous region of 16 amino acids is also shared between cap42(a), gelsolin and the Acanthamoeba profilins. Cap42(a) binds two actin molecules in a similar way to gelsolin suggesting a mechanism of F-actin modulation that has been conserved during evolution.

Actin Depolymerizing Factors↗

PubMed1987

The amino acid sequence of protein II and its phosphorylation site for protein kinase C; the domain structure Ca2+-modulated lipid binding proteins.

Protein II isolated from porcine intestinal epithelium is a Ca2+-modulated lipid-binding protein. The amino acid sequence of porcine protein II reported here sheds new light on the properties of a multigene protein family which includes the tyrosine kinase substrates of the sarc gene (p36) and of the EGF-receptor (p35). The sequence consolidates the structural principle in which an amino-terminal tailpiece of variable length is followed by a core built from four internally homologous segments for those proteins in the 35-40 kd range. Sequence data also show that the core can now be described as two domains each containing one low and one high homology segment. This view accounts for two Ca2+ sites, lipid aggregation and F-actin bundling--when present--and suggests that properties of the cores in which protein II differs from p36 and p35 arise primarily from segments 1 and 2. The protease-sensitive tailpiece of protein II is very short and lacks the phosphorylatable tyrosine present in the larger tail domains of p36 and p35. It harbors, however, like the p36 domain, the major site for in vitro phosphorylation by the Ca2+- and lipid-activated protein kinase C. In protein II this site is most likely threonine 6. The sequence alignment also explains why protein II does not interact with a unique p11, a property probably specific for p36. Our results further suggest that liver endonexin may reflect two protein species both closely related to protein II.

Amino Acid Sequence↗

PubMed1986

Structural and functional analysis of a cloned delta endotoxin of Bacillus thuringiensis berliner 1715.

A plasmid-encoded crystal protein gene (bt2) has been cloned from Bacillus thuringiensis berliner 1715. In Escherichia coli, it directs the synthesis of the 130-kDa protein (Bt2) which is toxic to larvae of Pieris brassicae and Manduca sexta. Comparison of the deduced amino acid sequence of this Bt2 protein with the B. thuringiensis kurstaki HD1 Dipel, B. thuringiensis kurstaki HD73 and B. thuringiensis sotto crystal protein sequences suggests that homologous recombination between the different genes has occurred during evolution. Treatment of the Bt2 protein with trypsin or chymotrypsin yields a 60-kDa protease-resistant and fully toxic polypeptide. The minimal portion of the Bt2 protein required for toxicity has been determined by analysing the polypeptides produced by deletion derivatives of the bt2 gene. It coincides with the 60-kDa protease-resistant Bt2 fragment and it starts between amino acids 29 and 35 at the N-terminus and terminates between positions 599 and 607 at the C-terminus.

Amino Acid Sequence↗

PubMed1986

The amino-acid sequence of the 2S sulphur-rich proteins from seeds of Brazil nut (Bertholletia excelsa H.B.K.).

Storage proteins of the albumin solubility fraction from seeds of Bertholletia excelsa H.B.K. were separated by reversed-phase high-performance liquid chromatography and their primary structures were determined by gas-phase sequencing on intact polypeptides and on the overlapping tryptic and thermolysin peptides. The 2S storage proteins consist of two subunits linked by disulphide bridges. The large subunit (8.5 kDa) is expressed in at least six different isoforms while the small subunit (3.6 kDa) consists of only one form. These proteins are extremely rich in glutamine, glutamic acid, arginine and the sulphur-containing amino acids cysteine and methionine. One of the variants even contains a sequence of six methionine residues in a row. Comparison with known sequences of 2S proteins of other dicotyledonous plants shows limited but distinct sequence homology. In particular, the positions of the cysteine residues relative to each other appear to be completely conserved, suggesting that tertiary structure constraints imposed by disulphide bridges dominate sequence conservation. It has been proposed that the two subunits of a related protein (the Brassica napus storage protein) is cleaved from a precursor polypeptide [Crouch, M. L., Tenbarge, K. M., Simon, A. E. & Ferl, R. (1983) J. Mol. Appl. Genet. 2,273-283]. The amino acid sequence homology of the Brazil nut protein with the former suggests that a similar protein processing event could occur.

Amino Acid Sequence↗

PubMed1986

Protein-chemical identification of the major cleavage sites of the Ca2+ proteinase on murine vimentin, the mesenchymal intermediate filament protein.

Neutral thiol proteinases (calpains), activated by calcium are involved in the intracellular turnover of intermediate filaments but the precise position of the cleavage points has remained unknown. Here we identify by direct sequence analysis the major cleavage sites found when murine vimentin is digested by limited proteolysis in vitro with calpain purified from porcine kidney. Contrary to some previous suggestions, no absolute sequence specifity could be detected although 10 specific sites have been identified. This result is in line with the cDNA derived amino-acid sequence of a calpain, which pointed to a similarity of the catalytic site with the active sites in papain, cathepsin and actinidin. However, all major cleavage sites are located within regions of the vimentin molecule, which in current models of intermediate filament structure are thought to be non-helical: the amino-terminal headpiece, the carboxy-terminal tailpiece and the spacer separating the two major coiled-coil domains. The sequence information about the cleavage sites was extended to provide the amino-terminal 119 residues of murine vimentin.

Amino Acid Sequence↗

PubMed1985

The amino acid sequence of Acanthamoeba profilin.

The complete amino acid sequence of Acanthamoeba profilin was determined by aligning tryptic, chymotryptic, thermolysin, and Staphylococcus aureus V8 protease peptides together with the partial NH2-terminal sequences of the tryptophan-cleavage products. Acanthamoeba profilin contains 125 amino acid residues, is NH2-terminally blocked, and has trimethyllysine at position 103. At five positions in the sequence two amino acids were identified indicating that the amoebae express at least two slightly different profilins. Charged residues are unevenly distributed, the NH2-terminal half being very hydrophobic and the COOH-terminal half being especially rich in basic residues. Comparison of the Acanthamoeba profilin sequence with that of calf spleen profilin (Nystrom, L. E., Lindberg, U., Kendrick-Jones, J., and Jakes, R. (1979) FEBS Lett. 101, 161-165) reveals homology in the NH2-terminal region. We suggest, therefore, that this region participates in the actin-binding activity.

Amino Acid Sequence↗