Membrane phospholipid dynamics during cytokinesis: regulation of actin filament assembly by redistribution of membrane surface phospholipid.

To study molecular motion and function of membrane phospholipids, we have developed various probes which bind specifically to certain phospholipids. Using a novel peptide probe, RoO9-0198, which binds specifically to phosphatidylethanolamine (PE) in biological membranes, we have analyzed the cell surface movement of PE in dividing CHO cells. We found that PE was exposed on the cell surface specifically at the cleavage furrow during the late telophase of cytokinesis.

Dienogest, a synthetic steroid, suppresses both embryonic and tumor-cell-induced angiogenesis.

Orally administered dienogest (17alpha-cyanomethyl-17beta-hydroxy-estra-4,9-diene-3-one) is efficacious against human hormone-dependent cancer xenografts in severely immunodeficient mice and in rats with experimental endometriosis, but its mechanisms of action remain unclear. We assessed the effect of dienogest on angiogenesis, because these two diseases that are sensitive to dienogest are known to be angiogenesis-dependent. Topical dienogest treatment dose-dependently inhibited embryonic angiogenesis, the ID(50) value being 6.

Isolation of a Chinese hamster ovary cell mutant defective in intramitochondrial transport of phosphatidylserine.

A CHO-K1 cell mutant with a specific decrease in cellular phosphatidylethanolamine (PE) level was isolated as a variant resistant to Ro09-0198, a PE-directed antibiotic peptide. The mutant was defective in the phosphatidylserine (PS) decarboxylation pathway for PE formation, in which PS produced in the endoplasmic reticulum is transported to mitochondria and then decarboxylated by an inner mitochondrial membrane enzyme, PS decarboxylase. Neither PS formation nor PS decarboxylase activity was reduced in the mutant, implying that the mutant is defective in some step of PS transport.

The active form of the ferric heme in neutrophil cytochrome b(558) is low-spin in the reconstituted cell-free system in the presence of amphophil.

The spin state of the heme in superoxide (O(2)(.)(-))-producing cytochrome b(558) purified from pig neutrophils was examined by means of room-temperature magnetic circular dichroism (MCD) under physiological conditions. Cytochrome b(558) with varying amounts of low-spin and high-spin heme was prepared by either pH adjustment or heat treatment, and the O(2)(.

Schizosaccharomyces pombe UDP-galactose transporter: identification of its functional form through cDNA cloning and expression in mammalian cells.

The Schizosaccharomyces pombe UDP-galactose transporter cDNA (SpUGT cDNA), encoding the product of the gms1+ gene which consists of two exon sequences separated by a 173-bp intron, was cloned by RT-PCR. Its product, a hydrophobic protein of 353 amino acid residues resembling its human counterpart, was expressed in the Golgi membranes of UDP-galactose transporter-deficient Lec8 cells, and complemented the genetic defect of the mutant cells. This indicated that SpUGT cDNA encodes the functional S.

Chemical modification of an arginine residue in the ATP-binding site of Ca2+ -transporting ATPase of sarcoplasmic reticulum by phenylglyoxal.

Phenylglyoxal (PGO) was used as a reagent for chemical modification of the ATP-binding site of Ca2+ -transporting ATPase of rabbit skeletal muscle sarcoplasmic reticulum (SR-ATPase). When 1 mM PGO was reacted with SR-ATPase at 30 degrees C at pH 8.5, PGO was bound to the ATPase molecule in two-to-one stoichiometry with concomitant loss of activity of the ATPase to form the phosphorylated intermediate (E-P).

A monoclonal antibody, 3A10, recognizes a specific amino acid sequence present on a series of developmentally expressed brain proteins.

Immunoblotting showed that a monoclonal antibody, 3A10, binds to a series of rat brain-specific antigens with molecular masses of 150-, 120-, 118-, 106-, 104-, 79-, and 77-kDa. The expression of 3A10 antigens is dependent on the developmental stage of the brain; only the 106-kDa antigen is detected during embryonic stages of rat brain development, while the expression of the remaining 6 antigens starts after birth and reaches a maximum during postnatal days 15-21. Detection of the 3A10 antigens in cultured neuronal and glial cells derived from cerebral cortices of rat brain at embryonic day 18 showed that the 77-, 79-, 106-, and 150-kDa antigens are specifically expressed in neuronal cells.

Development of a sensitive and accurate enzyme-linked immunosorbent assay (ELISA) system that can replace HPLC analysis for the determination of N1,N12-diacetylspermine in human urine.

N1,N12-Diacetylspermine (DiAcSpm)-specific antibodies were raised in rabbits, using N-acetylspermine coupled to mercaptosuccinylated BSA via N-(4-maleimidobutyryloxy)-succinimide as an antigen. Highly DiAcSpm-specific antibodies were enriched from crude sera through a series of affinity-based fractionations. A competitive ELISA system, intended for measuring DiAcSpm in solution, was constructed using this antibody preparation, with N-acetylspermine coupled to a synthetic peptide via N-(8-maleimidocapryloxy)-succinimide as a solid phase antigen.

Functional expression of human golgi CMP-sialic acid transporter in the Golgi complex of a transporter-deficient Chinese hamster ovary cell mutant.

We recently described the cloning of putative human CMP-sialic acid transporter (hCST) cDNA [Ishida, N. et al. (1996) J.

Functional expression of the human UDP-galactose transporters in the yeast Saccharomyces cerevisiae.

We describe the functional expression of the putative human Golgi UDP-galactose transporters (hUGT1 and hUGT2) in the yeast Saccharomyces cerevisiae. Both hUGT1 and hUGT2 were expressed under the control of the yeast constitutive GAPDH promoter. The expression level of hUGT1 seemed to be considerably lower than that of hUGT2, although hUGT1 has an amino acid sequence identical to that of hUGT2 except for 5 amino acid residues at the C-terminus.

Induction of apoptosis by phosphatidylserine.

Treatment of Chinese hamster ovary (CHO) cells with phosphatidylserine (PS) caused cell death in a dose-dependent manner. Other phospholipids, such as phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, and phosphatidic acid, had no effect on cell viability. The cells incubated with PS became round and underwent a dramatic reduction of cellular volume while maintaining the membrane containment of cellular contents.

Localization of the phosphatidylserine-binding site of glyceraldehyde-3-phosphate dehydrogenase responsible for membrane fusion.

In this study, we demonstrated that glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a phosphatidylserine (PS)-binding protein and localized the putative PS-binding site involved in the membrane fusion induced by this enzyme. In an attempt to identify the PS-binding proteins, we raised polyclonal antibodies against a 15-amino-acid synthetic peptide (amino acid residues 390-403 of phosphatidylserine decarboxylase), which was shown to bind specifically to PS. One polyclonal antibody, designated aPSD-2, crossreacted with GAPDH, and its binding to GAPDH was inhibited by PS but not by other phospholipids such as phosphatidylethanolamine and phosphatidylinositol.

Expression of the human UDP-galactose transporter in the Golgi membranes of murine Had-1 cells that lack the endogenous transporter.

In our previous study, we demonstrated that UDP-galactose transporter cDNAs (hUGT1 and hUGT2) were able to complement the genetic defect of murine Had-1 cells that were deficient in the UDP-galactose transporter, and that the microsomal vesicles isolated from Had-1-transformants, which were obtained through transfection with these cDNAs, had recovered the ability to uptake UDP-galactose [Ishida, N. et al. (1996) J.

Analysis of the distribution of Na+/H+ exchanger isoforms among the plasma membrane subfractions of bovine kidney cortex: reevaluation of methods for fractionating the brush-border and the basolateral membranes.

Distribution of the NHE1 and the NHE3 isoforms of Na+/H+ exchanger in the plasma membranes of bovine kidney cortex was analyzed. Fractionation of the plasma membranes by centrifugation on a Percoll density gradient resulted in clear separation of the basolateral membranes (BLM) from the brush-border membranes (BBM), with Na+,K+-ATPase and aminopeptidase M as their respective marker enzymes. Under these conditions, a 110 kDa protein cross-reactive with an anti-NHE1 antibody was detected exclusively in the BLM fractions, while a 90 kDa protein cross-reactive with an anti-NHE3 antibody was detected in the BBM fractions.

Preparation of antibodies highly specific to N1,N8-diacetylspermidine, and development of an enzyme-linked immunosorbent assay (ELISA) system for its sensitive and specific detection.

N8-Acetylspermidine was coupled to mercaptosuccinylated BSA using a bifunctional cross-linker, N-(4-maleimidobutyryloxy)succinimide, and the resulting conjugate was used to raise N1,N8-diacetylspermidine (DiAcSpd)-specific antibodies in rabbits. DiAcSpd-specific antibodies were enriched from crude sera through a series of affinity-based fractionations using ligands with structures mimicking those of DiAcSpd and monoacetylspermidines. With the N8-acetylspermidine-BSA conjugate as a solid phase antigen in a competitive ELISA system, the selectivity for DiAcSpd over other polyamine species was high, but competition by DiAcSpd added to the fluid phase was too weak for the system to be applicable to measurement of the concentration of DiAcSpd in human urine.