PubMed Health⌕ Search

Biomedical subjects

M S Robinson

Publications and source records attributed to M S Robinson.

16 recordsLinked to original sources
PubMed1992

Recruitment of coat proteins onto Golgi membranes in intact and permeabilized cells: effects of brefeldin A and G protein activators.

Brefeldin A (BFA) causes a rapid redistribution of coat proteins (e.g., gamma-adaptin) associated with the clathrin-coated vesicles that bud from the trans-Golgi network (TGN), while the clathrin-coated vesicles that bud from the plasma membrane are unaffected. gamma-Adaptin redistributes with the same kinetics as beta-COP, a coat protein associated with the non-clathrin-coated vesicles that bud from the Golgi complex. Upon removal of BFA, however, gamma-adaptin recovers its perinuclear distribution more rapidly. Redistribution of both proteins can be prevented by pretreating cells with AlF4-. Recruitment of adaptors from the cytosol onto the TGN membrane has been reconstituted in a permeabilized cell system and is increased by addition of GTP gamma S and blocked by addition of BFA. These results suggest a role for G proteins in the control of the clathrin-coated vesicle cycle at the TGN and further extend the similarities between clathrin-coated vesicles and non-clathrin-coated vesicles.

Adaptor Protein Complex alpha Subunits↗
PubMed1991

Children's attributions for peers' positive behaviors: social status differences.

The purpose of this study was to investigate differences between aggressive-rejected and nonaggressive-cooperative boys in their attributions for peers' positive behaviors. In individual interviews, 27 aggressive-rejected and 27 nonaggressive-accepted boys were presented with 10 vignettes and a real-life situation in which a peer's action resulted in a favorable outcome for another peer or for the subject. Subject's attributions for the peer's behavior were elicited with open-ended probes. Analysis of variance indicated that the groups did not differ in their tendency to infer positive intentions in the hypothetical story condition. In the real-life situation, aggressive-rejected boys were less likely to infer positive intentionality than were the nonaggressive-accepted boys. Boys' responses across the two conditions (hypothetical and real life) were moderately consistent.

Aggression↗
PubMed1990

Conservation and diversity in families of coated vesicle adaptins.

The complete sequence of the beta adaptin subunit of the plasma membrane adaptor complex from coated vesicles has been elucidated. Complementary cDNA clones from human fibroblasts, rat lymphocytes, and bovine lymphocytes have been isolated, sequenced, and compared with each other and with beta adaptin sequences from rat brain (Kirchhausen, T., Nathanson, K.L., Matsui, W., Vaisberg, A., Chow, E.P., Burne, C., Keen, J.H., and Davis, A.E. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 2612-2616). Surprisingly, the 937-amino acid beta adaptin polypeptide is totally conserved between species. This remarkable homology contrasts with the absence of significant sequence similarity between the alpha (Robinson, M.S. (1989) J. Cell Biol. 108, 833-842) and beta adaptins of the plasma membrane adaptor complex. Diversity within each adaptin family is created by the expression of different genes and by tissue-specific differential splicing. The structures of the beta and alpha adaptins can both be divided into two globular domains interconnected by a variable and potentially flexible stalk domain.

Adaptor Protein Complex alpha Subunits↗
PubMed1990

Cloning and expression of gamma-adaptin, a component of clathrin-coated vesicles associated with the Golgi apparatus.

Adaptins are the major components of adaptors, the protein complexes that link clathrin to transmembrane proteins (e.g., receptors) in coated pits and vesicles. The plasma membrane adaptor contains an alpha-adaptin subunit and a beta-adaptin subunit, while the Golgi adaptor contains a gamma-adaptin subunit and a beta'-adaptin subunit. A partial cDNA clone encoding gamma-adaptin was isolated from a bovine brain expression library by screening with antibodies, and was used to obtain a cDNA clone from a mouse brain library containing the full coding sequence. The identity of the clones was confirmed by protein sequencing. The deduced amino acid sequence of gamma-adaptin was found to be homologous to that of alpha-adaptin, with several stretches of identical amino acids or conservative substitutions in the first approximately 70 kD, and 25% identity overall. Weaker homology was seen between gamma- and beta-adaptins. Like both alpha- and beta-adaptins, gamma-adaptin has a proline and glycine-rich hinge region, dividing it into NH2- and COOH-terminal domains. A chimeric gamma-adaptin was constructed from the mouse and bovine cDNAs and transfected into Rat 1 fibroblasts. Immunofluorescence microscopy was carried out using an mAb which recognizes an epitope present on the chimera but not found on the rodent protein. The construct was found to have a distribution typical of endogenous gamma-adaptin. Using this transfection system, it should now be possible to exchange domains between alpha- and gamma-adaptins, to try to find out how adaptors are targeted to the appropriate membrane compartment of the cell, and how they recruit the appropriate receptors into the coated vesicle.

Adaptor Protein Complex gamma Subunits↗
PubMed1990

Dance-based aerobic exercise for rheumatoid arthritis.

Reported here are the results of the first effort to examine the effects of a dance-based aerobic exercise program for people with rheumatoid arthritis (RA). Forty-three subjects with RA completed a 16-week program that met twice weekly for 2 hours. One hour was devoted to exercise consisting of 15 to 20 minutes of warm-ups, 20 to 30 minutes of dance-based aerobic exercise, and 15 to 20 minutes of mat work for muscle strengthening and flexibility. The second hour was devoted to discussion that emphasized participant problem solving. The combined exercise/problem-solving discussion program was called EDUCIZE. Analyses of pretest to posttest changes indicated no deleterious effects on disease activity. In fact, physician-assessed articular pain and swelling decreased significantly, as did 50-foot walk time, pain, and depression. Participants reported significant improvement in lower extremity function. Changes in vigor and fatigue approached significance. Perceptions of general health as well as four of five quality of life indices improved significantly. This study adds to the as yet limited literature that indicates that weight-bearing vigorous exercise is beneficial for people with arthritis. Controlled studies to validate the findings of this study appear warranted. Also important for future research is investigation of the influence of the problem-solving discussion component on program effects.

Adult↗
PubMed1989

Cloning of cDNAs encoding two related 100-kD coated vesicle proteins (alpha-adaptins).

Coat proteins of approximately 100-kD (adaptins) are components of the adaptor complexes which link clathrin to receptors in coated vesicles. The alpha-adaptins, which are found exclusively in endocytic coated vesicles, separate into two bands on SDS gels, designated A and C (Robinson, M. S., 1987. J. Cell Biol. 104:887-895). Two distinct cDNAs (sequences 1 and 2) encoding the two alpha-adaptins were cloned from a mouse brain cDNA library. Southern blotting indicates that there is one copy of each of the two alpha-adaptin genes, and that there are no additional closely related genes. Based on the size of the predicted protein products of the two genes (108 and 104 kD), the relative abundance of the two messages in brain and liver, and the reactivity of a sequence 1 fusion protein with different antibodies, it was possible to conclude that sequence 1 codes for A and sequence 2 for C. The two protein sequences are strikingly homologous to each other (84% identical amino acids), the major difference being an additional stretch of 41 amino acids, rich in prolines and acidic residues, inserted into the COOH-terminal half of A. In situ hybridization carried out on mouse brain sections indicates that the same cell type may express both transcripts, but that their relative expressions vary. Antipeptide antibodies are now being raised to find out whether the proteins are localized in functionally distinct populations of endocytic coated vesicles.

Adaptor Protein Complex alpha Subunits↗
PubMed1987

100-kD coated vesicle proteins: molecular heterogeneity and intracellular distribution studied with monoclonal antibodies.

Proteins with molecular weights of around 100,000 (designated 100K) are found in all coated vesicles. Five monoclonal antibodies have been raised against the major 100K proteins of bovine brain coated vesicles, which migrate on SDS gels as three closely spaced bands. One antibody stains the middle band (band B), two stain both upper and lower bands (bands A and C), and two stain the lower band (band C) only. Thus, the polypeptides in bands A and C are related (but not identical), a result confirmed by NH2-terminal sequencing. Other tissues were found to express proteins corresponding to, and co-migrating with, bands B and C but not band A. Only the two antibodies that recognize both A and C stained fixed and permeabilized tissue culture cells; they both showed a punctate pattern in the plane of the plasma membrane. Double labeling with anti-clathrin antibodies confirmed that the dots correspond to coated pits and vesicles. However, perinuclear staining seen with anti-clathrin, corresponding to Golgi-derived coated vesicles, was conspicuously absent with the two monoclonal antibodies. Affinity-purified polyclonal antisera against the 100K proteins, reported earlier, gave perinuclear as well as punctate staining; these included one antiserum which gave mainly perinuclear staining (Robinson, M. S., and B. M. F. Pearse, 1986, J. Cell Biol., 102:48-54). Thus, different 100K proteins appear to be found in different membrane compartments. Since the 100K proteins are thought to lie between clathrin and the membrane proteins of the vesicle, these results may help to explain how different membrane proteins can be sorted into coated vesicles in different parts of the cell.

Amino Acid Sequence↗
PubMed1986

Immunofluorescent localization of 100K coated vesicle proteins.

A family of coated vesicle proteins, with molecular weights of approximately 100,000 and designated 100K, has been implicated in both coat assembly and the attachment of clathrin to the vesicle membrane. These proteins were purified from extracts of bovine brain coated vesicles by gel filtration, hydroxylapatite chromatography, and preparative SDS PAGE. Peptide mapping by limited proteolysis indicated that the polypeptides making up the three major 100K bands have distinct amino acid sequences. When four rats were immunized with total 100K protein, each rat responded differently to the different bands, although all four antisera cross-reacted with the 100K proteins of human placental coated vesicles. After affinity purification, two of the antisera were able to detect a 100K band on blots of whole 3T3 cell protein and were used for immunofluorescence, double labeling the cells with either rabbit anti-clathrin or with wheat germ lectin as a Golgi apparatus marker. Both antisera gave staining that was coincident with anti-clathrin, with punctate labeling of the plasma membrane and perinuclear Golgi apparatus labeling. Thus, the 100K proteins are present on endocytic as well as Golgi-derived coated pits and vesicles. The punctate patterns were nearly identical with anti-100K and anti-clathrin, indicating that when vesicles become uncoated, the 100K proteins are removed as well as clathrin. One of the two antisera gave stronger plasma membrane labeling than Golgi apparatus labeling when compared with the anti-clathrin antiserum. The other antiserum gave stronger Golgi apparatus labeling. Although we have as yet no evidence that these two antisera label different proteins on blots of 3T3 cells, they do show differences on blots of bovine brain 100K proteins. This result, although preliminary, raises the possibility that different 100K proteins may be associated with different pathways of membrane traffic.

Animals↗
PubMed1976

Characterization of the extracellular haemoglobin of Haemopsis sanguisuga (L.).

The haemoglobin from the blood of the horseleech, Haemopsis sanguisuga (L.), had a sedimentation coefficient, SO20, w, of 59.11 +/- 0.55 S, and a molecular weight as determined by sedimentation equilibrium of 3.71 X 10(6)+/-9904 X 10(6). In the electron microscope the molecule appeared to be made up of two hexagonal plates, as is found with other worm haemoglobins, with dimensions 24.4+/-2.0 nm (across the hexagon) and 15.2+/-1.4 nm (height). The amino acid composition and spectrum were closely similar to those of the haemoglobins of other annelids (e.g. Lumbricus). The alpha-helical content, calculated from circular-dichroism measurements in the far-u.v. region, was 56-63%. The haem content was 2.49%, corresponding to a minimum molecular weight per haem group of 24 800, but detergent-gel electrophoresis indicated the presence of polypeptide chains of mol.wts. 12 600, 14 800, 15 500 and 25 100. The pH-induced dissociation of the native molecule yielded compotosol of Soya-bean root nodules.

Amino Acids↗
PubMedDate not supplied

Competition for binding to multiple sites of human serum albumin for cholecystographic agents and sulfobromophthalein.

The binding of two cholecystographic agents, iophenoxate and iopanoate, to human serum albumin was studied with 11 putative competitors; the results were qualitatively consistent with competitive binding to common sites. A more precise analysis of competition was achieved with four pairs of compounds for which the free and bound concentration of each was determined. The results were analyzed by a computer program and the dissociation constants calculated for both binder and competitor at specified sites on albumin. With numbering based on the rank order of dissociation constants for iophenoxate, the highest binding of the four compounds occurs at different sites: iophenoxate at site I; iopanoate at site II, sulfobromophthalein at site III; and bromphenol blue at site II. For a given compound, there is close agreement in the calculated affinities at different sites regardless of the competitor.

Binding Sites↗