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R Fletterick

Publications and source records attributed to R Fletterick.

24 records · Page 2Linked to original sources
PubMed1985

Redesigning trypsin: alteration of substrate specificity.

A general method for modifying eukaryotic genes by site-specific mutagenesis and subsequent expression in mammalian cells was developed to study the relation between structure and function of the proteolytic enzyme trypsin. Glycine residues at positions 216 and 226 in the binding cavity of trypsin were replaced by alanine residues, resulting in three trypsin mutants. Computer graphic analysis suggested that these substitutions would differentially affect arginine and lysine substrate binding of the enzyme. Although the mutant enzymes were reduced in catalytic rate, they showed enhanced substrate specificity relative to the native enzyme. This increased specificity was achieved by the unexpected differential effects on the catalytic activity toward arginine and lysine substrates. Mutants containing alanine at position 226 exhibited an altered conformation that may be converted to a trypsin-like structure upon binding of a substrate analog.

Amino Acid Sequence↗
PubMed1984

Crystallization of the gene 45 protein from the DNA replication fork of bacteriophage T4.

The gene 45 protein from bacteriophage T4 has been purified and is crystallized. This protein is part of the T4 DNA replication complex. The crystallized protein is active in complementation assays. X-ray diffraction analysis is in progress; data are measured for the native and several heavy atom derivatives. The crystals diffract to about 3.5-A resolution.

Crystallization↗
PubMed1983

Splice junctions: association with variation in protein structure.

A comparison between eukaryotic gene sequences and protein sequences of homologous enzymes from bacterial and mammalian organisms shows that intron-exon junctions frequently coincide with variable surface loops of the protein structures. The altered surface structures can account for functional differences among the members of a family. Sliding of the intron-exon junctions may constitute one mechanism for generating length polymorphisms and divergent sequences found in protein families. Since intron-exon junctions map to protein surfaces, the alterations mediated by sliding of these junctions can be effected without disrupting the stability of the protein core.

Amino Acid Sequence↗
PubMed1982

Intron-exon splice junctions map at protein surfaces.

There have been several suggested explanations for the presence of noncoding intervening sequences in many eukaryotic structural genes. They may be examples of 'selfish DNA, conferring little phenotypic advantage, or they may have some importance in gene expression and/or evolution. It has been suggested that each exon (coding sequence) may represent a structural or functional unit of the encoded protein, for which there is good evidence in the case of immunoglobulin and haemoglobin genes. Exon modification, duplication and recombination may thus be general mechanisms for the rapid evolution of eukaryotic structural genes. In many cases, however, it is not apparent that an exon corresponds to some specific feature of the encoded protein. We describe here evidence that intron-exon junctions usually map to amino acid residues located at the protein surface, suggesting a restriction on the permitted positions of introns within a gene.

Amino Acids↗