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Biomedical subjects

W J Rutter

Publications and source records attributed to W J Rutter.

281 records · Page 16Linked to original sources
PubMed1967

Glyceraldehyde-3-phosphate dehydrogenase variants in phyletically diverse organisms.

Electrophoretically distinct forms of glyceraldehyde-3-phosphate dehydrogenase (TDH) have been detected in turtle, perch, trout, spinach, and yeast. Multiple forms were not detected in rat, rabbit, chicken, frog, honey bee, Euglena, or Escherichia coli. The combination of two different subunits into tetramers is a probable explanation for the five-membered sets usually detected in extracts exhibiting TDH multiplicity.

Animals↗
PubMedDate not supplied

Cell-specific expression controlled by the 5'-flanking region of insulin and chymotrypsin genes.

DNA sequences containing the 5'-flanking regions of the insulin and chymotrypsin genes were linked to the coding sequence of the chloramphenicol acetyltransferase (CAT) gene. The insulin gene recombinant elicits preferential expression of CAT activity when introduced into cells producing insulin; similarly, the chymotrypsin gene recombinant elicits preferential expression in chymotrypsin-producing cells. Sequences located upstream of previously defined transcriptional control elements are essential for efficient expression in both cases.

Acetyltransferases↗
PubMedDate not supplied

Sequence of protein disulphide isomerase and implications of its relationship to thioredoxin.

The formation of disulphide bonds is essential to the structure and function of proteins. These bonds rapidly form either cotranslationally or immediately post-translationally in the lumen of the endoplasmic reticulum. Native disulphide pairing for such proteins has been achieved in vitro; however, the rates of reassembly are slow and the conditions non-physiological. To account for these observations, Anfinsen et al. proposed that a 'disulphide interchange protein' was the in vivo catalyst of disulphide bond rearrangement. Other groups discovered an activity with similar characteristics that catalysed the reductive cleavage of insulin and may be associated with insulin degradation, although this result has been disputed. The enzyme involved, protein disulphide isomerase (PDI; EC 5.3.4.1), may be the in vivo catalyst of disulphide bond formation. Here we describe the sequence of cloned rat liver PDI complementary DNA which predicts a protein with two distinct regions homologous with Escherichia coli thioredoxin, a known cofactor in oxidation-reduction reactions. Each of these regions contains the presumed active site sequence Trp-Cys-Gly-His-Cys-Lys, suggesting that PDI, similar in action to thioredoxin, catalyses disulphide bond interchange via an internal disulphide-sulphydryl interchange. The cDNA predicts a signal peptide consistent with the view that PDI is a luminal endoplasmic reticulum protein. PDI messenger RNA, although ubiquitous, is more highly concentrated in secretory cells.

Amino Acid Sequence↗
PubMedDate not supplied

Site-directed mutagenesis shows that tyrosine 248 of carboxypeptidase A does not play a crucial role in catalysis.

The residue Tyr 248 of carboxypeptidase A (CPA) is thought to play a role in catalysis by contributing a proton to the incipient amine anion generated during cleavage of peptide substrates. To test this hypothesis we have modified the rat CPA cDNA by site-directed mutagenesis so that the codon for Tyr 248 is replaced by that for Phe. Here, we report the expression of the cDNAs for proCPA and its Tyr-to-Phe variant in yeast via the alpha-factor system. Following zymogen activation by trypsin, wild-type CPA (CPA-WT) and variant CPA (CPA-Phe 248) were purified to homogeneity and characterized enzymatically. CPA-Phe 248 displays essentially undiminished values for the catalytic constant (kcat) towards various peptide and ester substrates. However, the Michaelis constants (Km values) of peptide substrates and the inhibition constant (Ki) of the potato carboxypeptidase inhibitor are increased 6-fold and 70-fold, respectively. These data suggest that the phenolic hydroxyl of Tyr 248 does not act as the requisite general acid catalyst but participates in ligand binding.

Amino Acid Sequence↗
PubMedDate not supplied

Differential RNA splicing predicts two distinct nerve growth factor precursors.

Nerve growth factor (NGF) has a crucial role in the development of sensory and sympathetic neurones. However, although it can affect other neural cell types under certain experimental conditions, no biological role has been convincingly demonstrated elsewhere in the nervous system. The 5' end of the mouse NGF gene contains several relatively short exons. The NGF messenger RNA contains two in-frame initiator methionine codons; the second precedes the signal peptide sequence. Studies of the translation of other eukaryotic mRNAs indicate that the first AUG is preferred, suggesting that the signal for secretion might be ambiguous. We have analysed the NGF mRNA species from various cell types, some of which (clonal myoblast and fibroblast cell lines) are known to secrete NGF, to search for different NGF transcripts. One pathway of RNA splicing generates the transcript already described from a submaxillary gland complementary DNA clone. We demonstrate here that there is another splicing pathway, leading to a shorter transcript that lacks the second exon. This short transcript is the major form in most other mouse tissues and in the tissues of several other species, but both transcripts are usually present. In the short transcript, the initiator methionine is immediately upstream from a signal peptide-like sequence whereas in the long transcript the first methionine is 62 amino acids upstream from the signal peptide-like sequences. This may result in a different cellular localization of the NGF or alter the biological activity of the NGF precursor.

Animals↗
PubMedDate not supplied

Insulin-like growth factor II receptor as a multifunctional binding protein.

The primary structure of human insulin-like growth factor II receptor, predicted from the complementary DNA sequence, reveals a transmembrane receptor molecule with a large extracellular domain made up of fifteen repeat sequences and a small region homologous to the collagen-binding domain of fibronectin. The structural and biochemical features of the IGF-II receptor appear identical to those of the cation-independent mannose-6-phosphate receptor.

Amino Acid Sequence↗