The effect of polyamines on the binding of aminoacyl transfer ribonucleic acid to ribosomes in a yeast system.
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Amines↗
Biomedical subjects
M J Tanner
Publications and source records attributed to M J Tanner.
Evidence that the Lub blood group antigen is located on red cell membrane glycoproteins of 85 and 78 kd.
A murine monoclonal antibody of specificity anti-Lub was produced. Immunoblotting of the electrophoretically separated components of membranes from Lu(b+) red cells with the monoclonal antibody identified two glycoproteins of relative molecular mass 85 and 78 kd, respectively. The expression of Lub antigenic activity on these glycoprotein components was shown to be dependent on the presence of one or more N-glycosidically linked oligosaccharides and on the presence of disulphide bonding.
Antibodies, Monoclonal↗
Murine monoclonal antibody MB-2D10 recognizes Rh-related glycoproteins in the human red cell membrane.
The human red cell membrane components reacting with monoclonal antibody MB-2D10 were examined by immunoblotting. The antibody bound to a diffusely staining band extending from Mr 30,000 up to the high-molecular-weight region of the gel in normal membranes and in Rhnull U + membranes, but not in Rhnull U - membranes. Treatment of normal red cells with an endoglycosidase F-containing preparation destroyed the epitope recognized by MB-2D10. The reactivity of the antibody with purified preparations of Rh-related glycoproteins D30 polypeptide, D50 polypeptide, R6A32 polypeptide, and R6A45 polypeptide was also examined. Only the purified R6A45 and D50 components reacted with MB-2D10. These results show that MB-2D10 recognizes a carbohydrate-dependent epitope on the R6A45 and D50 group of Rh-related polypeptides. The results also suggest the possibility that the U antigen arises from interaction between glycophorin B and the Rh-related components D50 and R6A45.
Animals↗
The Wrb antigen in Sta-positive and Dantu-positive human erythrocytes.
Immunoprecipitation using a monoclonal antibody showed that the Wrb antigen is present on the abnormal (delta-alpha) hybrid sialoglycoprotein of Sta-positive human erythrocytes but not on the abnormal (delta-alpha) hybrid sialoglycoprotein of Dantu-positive erythrocytes. These results provide further information regarding the nature and location of the Wrb antigen on the normal erythrocyte sialoglycoprotein alpha.
Amino Acid Sequence↗
Functional factors in the red cell membrane: interactions between the membrane and its underlying skeleton.
Recent studies involving two abnormal red cell phenotypes (South-east Asian ovalocytosis and Leach phenotype) provide novel information concerning the nature and significance of interactions of both the anion transport protein AE-1 (syn. band 3) and Glycophorins C and D with the underlying skeleton. The location of Wra and Dia blood group antigens to mutations on AE-1 at residues 658 and 854 respectively, together with the availability of monoclonal antibodies recognising epitopes dependent upon the integrity of the third extracellular loop of AE-1, have allowed us to study the organisation of the membrane domain of the mutant AE-1 found in South-east Asian ovalocytes (AE-1 SAO). The results suggest that the organisation of the whole membrane domain of AE-1 SAO is abnormal and that the organisation of other integral membrane proteins like those involved in expression of Rh blood group antigens may also be affected. Increased homo- and hetero-associations involving AE-1 SAO and other integral proteins may in turn result in reduced membrane flexibility. Purified protein 4.1 binds with 50-fold higher affinity to protein 4.1 depleted normal red cell membranes than to protein 4.1 depleted red cell membranes of Leach phenotype which lack Glycophorin C (GPC) and Glycophorin D (GPD). Experiments using purified protein 4.1 and p55 together with synthetic peptides corresponding to different regions of the cytoplasmic domain of Glycophorins C and D (GPC/D) demonstrate that protein 4.1 interacts directly with GPC through residues 82-98. They also show that p55 binds to GPC through residues 112-128. Since p55 also binds directly to protein 4.1 it is clear that protein 4.1 can bind to GPC through two different sites either directly through residues 82-98 or indirectly through p55. These results show that GPC and GPD provide major attachment sites for the red cell skeleton via protein 4.1 and that p55 is part of this complex.
Anion Exchange Protein 1, Erythrocyte↗
Role of N-glycosylation in the expression of human band 3-mediated anion transport.
The human erythrocyte anion transporter (band 3; AE1) has a single N-linked glycosylation site at amino residue Asn-642. To investigate the functional role of the N-glycan in band 3 (b3) we have constructed mutant b3 cDNAs in which this residue has been replaced by Gly, Ser or Thr, and the expression of these mutants was examined in Xenopus oocytes. Chymotrypsin treatment of intact oocytes was used to assess surface b3. Similar amounts of cleavage were observed with both glycosylated and unglycosylated b3. Greater cleavage of b3 was obtained when human red cell glycophorin A (GPA) was co-expressed with either glycosylated or unglycosylated b3. The co-expression of GPA with either glycosylated or unglycosylated b3 increased the stilbene disulphonate-sensitive chloride transport into oocytes at low cRNA concentrations. In both the presence or absence of GPA, a higher b3-mediated chloride influx into oocytes was observed on expression of glycosylated b3 cRNA compared with similar amounts of unglycosylated b3 cRNA. We suggest that glycosylation is not essential for the expression of functional b3 in oocytes, but may play a role in enabling the protein to acquire its correct folding with the highest anion transport activity.
Animals↗
The structure and function of band 3 (AE1): recent developments (review).
This review discusses recent advances in our understanding of the structure, function and molecular genetics of the membrane domain of red cell anion exchanger, band 3 (AE1), and its role in red cell and kidney disease. A new model for the topology of band 3 has been proposed, which suggests the membrane domain has 12 membrane spans, rather than the 14 membrane spans of earlier models. The major difference between the models is in the topology of the region on the C-terminal side of membrane spans 1-7. Two dimensional crystals of the deglycosylated membrane domain of band 3 have yielded two and three dimensional projection maps of the membrane domain dimer at low resolution. The human band 3 gene has been completely sequenced and this has facilitated the study of natural band 3 mutations and their involvement in disease. About 20% of hereditary spherocytosis cases arise from heterozygosity for band 3 mutations, and result in the absence or decrease of the mutant protein in the red cell membrane. Several other natural band 3 mutations are known that appear to be clinically benign, but alter red cell phenotype or are associated with altered red cell blood group antigens. These include the mutant band 3 present in Southeast Asian ovalocytosis, a condition which provides protection against cerebral malaria in children. Familial distal renal tubular acidosis, a condition associated with kidney stones, has been shown to result from a novel group of band 3 mutations. The total absence of band 3 has been described in animals-occurring naturally in cattle and after targeted disruption in mice. Some of these severely anaemic animals survive, so band 3 is not strictly essential for life. Although the band 3-negative red cells were very unstable, they contained a normally-assembled red cell skeleton, suggesting that the bilayer of the normal red cell membrane is stabilized by band 3 interactions with membrane lipids, rather than by interactions with the spectrin skeleton.
Amino Acid Sequence↗
Studies on the blood of an MiV homozygote.
An individual, whose parents are third cousins, has been shown to be homozygous for the rare Mi.V. condition. The proposita's red blood cells type as M-, N+(weak), S-, s+(strong), U+, Mi(a-), Vw-, Hil+; Wr(a-b-). The cells react, albeit less strongly than most other samples, with anti-Ena. However, from studies on the red blood cells of the proposita and on those of another person of the En(a+), Wr(a-b-) phenotype, it is apparent that the term "anti-Ena" actually describes a number of antibodies of differing specificities. Inhibition studies with sialoglycoprotein (SGP) isolates, and tests on protease-modified red blood cells illustrate some of the differences in specificity. Biochemical analyses of the SGPs of the red blood cells of the MiV homozygote and those of her parents confirm that the Mi.V condition is associated with the absence of normal MN SGP (alpha) and normal Ss SGP (delta), the appearance of a hybrid SGP molecule comprised of a portion of the MN SGP at its NH2 terminal end, and a portion of the Ss SGP at its C terminal end.
Animals↗