Methemoglobin reduction mediated by D-amino acid dehydrogenase in Propsilocerus akamusi (Tokunaga) larvae.

A methemoglobin (metHb) reduction system is required for aerobic respiration. In humans, Fe(III)-heme-bearing metHb (the oxidized form of hemoglobin), which cannot bind oxygen, is converted to Fe(II)-heme-bearing oxyhemoglobin (oxyHb, the reduced form), which can bind oxygen, in a system comprising NADH, NADH-cytochrome b5 reductase, and cytochrome b5. However, the mechanism of metHb reduction in organisms that inhabit oxygen-deficient environments is unknown.

Methemoglobin reduction by NADH-cytochrome b(5) reductase in Propsilocerus akamusi larvae.

For oxygen respiration, a methemoglobin (metHb) reduction system is needed in the cell because metHb cannot bind oxygen. We examined the insect Propsilocerus akamusi larvae to elucidate the metHb reduction system in an organism that inhabits an oxygen-deficient environment. NADH-dependent reduction of metHb in coelomic fluid suggested the coexistence of cytochrome b5 reductase (b5R) and cytochrome b5 with hemoglobin in the fluid and that these proteins were involved in physiological metHb reduction in the larvae.

cDNA cloning and life-cycle stage-specific expression of coronin from Physarum polycephalum.

Coronin cDNA was cloned from the plasmodia of Physarum polycephalum. The amino acid sequence deduced from the cDNA was comprised of 449 residues and showed 60% identity to that of Dictyostelium discoideum coronin. Southern blot analysis suggested that the coronin gene present in the P.

Properties, intracellular localization, and stage-specific expression of membrane-bound beta-glucosidase, BglM1, from Physarum polycephalum.

Physarum polycephalum expresses a membrane-bound beta-glucosidase (BglM1) with a molecular mass of 130 kDa. The primary structure of BglM1 consists of a glycosyl hydrolase family 3 domain at an amino-terminal domain and a carboxyl-terminal region without homology to the sequence of known glycosidases. The latter region contains two calx-beta motifs known as Ca(2+)-binding sites; an RGD sequence, which is known to be a cell attachment sequence; and a transmembrane region.

Structure of Physarum polycephalum cytochrome b5 reductase at 1.56 A resolution.

Physarum polycephalum cytochrome b(5) reductase catalyzes the reduction of cytochrome b(5) by NADH. The structure of P. polycephalum cytochrome b(5) reductase was determined at a resolution of 1.

Structure and properties of the recombinant NADH-cytochrome b5 reductase of Physarum polycephalum.

A cDNA for NADH-cytochrome b(5) reductase of Physarum polycephalum was cloned from a cDNA library, and the nucleotide sequence of the cDNA was determined (accession no. AB259870). The DNA of 943 base pairs contains 5'- and 3'-noncoding sequences, including a polyadenylation sequence, and a coding sequence of 843 base pairs.

A cDNA cloned from Physarum polycephalum encodes new type of family 3 beta-glucosidase that is a fusion protein containing a calx-beta motif.

The microplasmodia of Physarum polycephalum express three types of beta-glucosidases: secretory enzyme, a soluble cytoplasmic enzyme and a membrane-bound enzyme. We are interested in the physiological role of three enzymes. We report the sequence of cDNA for membrane beta-glucosidase 1, which consists of 3825 nucleotides that includes an open reading frame encoding 1248 amino acids.

Dihydroceramide:sphinganine C-4-hydroxylation requires Des2 hydroxylase and the membrane form of cytochrome b5.

Des2 (degenerative spermatocyte 2) is a bifunctional enzyme that produces phytoceramide and ceramide from dihydroceramide. The molecular mechanism involved in C-4-hydroxylation has not been studied in detail. In the present paper, we report that C-4-hydroxylation requires an electron-transfer system that includes cytochrome b5 and that the hydroxylase activity is reconstituted in an in vitro assay with purified recombinant Des2.

Analysis of six new genes encoding lysis proteins and coat proteins in Escherichia coli group A RNA phages.

Group A RNA phages consist of four genes-maturation protein, coat protein, lysis protein and replicase genes. We analyzed six plasmids containing lysis protein genes and coat protein genes of Escherichia coli group A RNA phages and compared their amino acid sequences with the known proteins of E. coli(group A), Pseudomonas aeruginosa(PP7) RNA phages and Rg-lysis protein from Qbeta phage.

An ascidian homologue of the gonadotropin-releasing hormone receptor is a retinoic acid target gene.

Transdifferentiation of the multipotent atrial epithelium is a key event during budding of the ascidian Polyandrocarpa misakiensis. The transdifferentiation is induced by mesenchyme cells that were stimulated by retinoic acid. The fluorescent differential display identified a few cDNA fragments for retinoic acid-inducible genes.

Structure of human erythrocyte NADH-cytochrome b5 reductase.

Erythrocyte NADH-cytochrome b(5) reductase reduces methaemoglobin to functional haemoglobin. In order to examine the function of the enzyme, the structure of NADH-cytochrome b(5) reductase from human erythrocytes has been determined and refined by X-ray crystallography. At 1.

Structure of a cDNA for Ciona Cytochrome b(5) and the ubiquitous expression of mRNA in embryonic tissues.

A cDNA clone for cytochrome b(5) was isolated from a cDNA library of an ascidian, Ciona savignyi, by a plaque hybridization method using a digoxigenin-labeled cDNA for the soluble form of human cytochrome b(5). The cDNA is composed of 5'- and 3'-noncoding sequences, and a 396-base pair coding sequence. The 3'-noncoding sequence contains polyadenylation signal sequences.

Phospholipids and their derivatives as mitogen and motogen of budding tunicates.

In order to discover novel invertebrate cytokines from the budding tunicate, Polyandrocarpa misakiensis, we treated the water-insoluble fraction of tunicate homogenates with trypsin. The extracts showed remarkable activities to promote the growth and motility of tunicate cells. The activities were heat-stable and proteinase K-resistant.