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C Mulet

Publications and source records attributed to C Mulet.

15 recordsLinked to original sources
PubMed1981

Selective expression of blood group antigens on human teratocarcinoma cell lines.

The presence of the blood group antigens H, P, Pk as well as the T-antigen of Thomsen-Friedenreich (detected by the PNA lectin) was investigated at the surface of human embryonal carcinoma cells and of normal or tumor cell lines from adult individuals by an indirect immunofluorescence method. The PNA lectin binds to all the teratoma cell lines investigated but only occasionally to the adult cell lines. The H antigen was detected by fluorescence only onto the embryonic carcinoma cell PA1, but the H enzyme (2-alpha-L-fucosyltransferase) was found catalytically active in all teratoma cells tested: PA1, Susa, Tera I and Tera Ii. Finally, it was also shown that P and Pk antigens are expressed very early during development, prior to HLA and H or ABO.

ABO Blood-Group System↗
PubMed1980

Different H deficient phenotypes present in one kindred.

Two different H deficient phenotypes are observed in one kindred. Three of them in two generations of a same family appear as Bombay like. In the other branch of the kindred, an Hz phenotype (as described in the editorial of this issue) is observed. The most simple explanation is that the three Bombay like phenotypes correspond to Hz ABH non secretor (Hz sese) individuals, this being indistinguishable from a true Bombay. The high level of I antigen in the plasma of the three Bombay like (as observed in Hz in contrast to true Bombay) could favour such an hypothesis. According to ORIOL'S new hypothesis [5], III2, III3 and IV2 would genetically be hh sese, III8 would be hh Se and the h Se would therefore be a recombining haplotype (the original haplotype being h se).

ABO Blood-Group System↗
PubMed1980

ABH and Lewis glycosyltransferases in human red cells, lymphocytes and platelets.

The alpha-O-N-acetylgalactosaminyl-, alpha-3-D-galactosyl- and alpha-2-L-fucosyltransferases, the direct products of the respective A, B and H blood group genes have been identified in red cells, lymphocytes and platelets homogenates from secretor and non-secretor individuals of appropriate ABO group. The H enzyme was not detectable in red cell membranes from Bombay individuals. Since the uptake of A antigen from the plasma has been shown at least for red cells [10] and lymphocytes [25], the present results suggest that the ABH determinants of the blood cells may arise both from intrinsic and extrinsic origin, but the relative contribution of each mechanism is not known. In contrast, the Lewis enzyme was absent or inactive in all the investigated blood cell samples, which can be considered as an additional proof that the Lewis antigens of these cells are entirely derived from the plasma.

ABO Blood-Group System↗
PubMed1980

Bromopyruvate as an affinity label for baker's yeast flavocytochrome b2. Stoichiometry of incorporation and localization on the peptide chain.

We have reported in a previous communication a kinetic study showing bromopyruvate to behave as an active-site-directed reagent for flavocytochrome b2. It is shown here that inactivation is accompanied by incorporation of 3 mol reagent/subunit of oxidized intact enzyme and 4 mol reagent/subunit nicked enzyme. Only one of the modifications is presumed to be responsible for activity loss. All labeled groups are found to be cysteines. Incubation of reduced nicked enzyme with bromopyruvate results in total protection of activity and loss of only one sulfhydryl group. A subsequent incubation in the presence of the competitive inhibitor sulfite leads to some more loss of non-essential groups. After these two pretreatments, incubation in the presence of bromo[2-14C]pyruvate results in incorporation of 1.2--1.5 mol reagent/subunit concomitant with the loss of about 0.8 active site. A study of the distribution of label between fragments alpha and beta has been carried out using gel electrophoresis and Sephadex filtration after selective proteolysis. It is shown that the active-site sulfhydryl group corresponds to one of the four cysteines situated in the last two thirds of fragment alpha. The structural and functional implications of these results is discussed.

Affinity Labels↗
PubMed1979

Probable biosynthetic pathway for the synthesis of the B antigen for Bh variants.

Red cells and serum from two Bh variants (B+H-cells) have been investigated for B and H blood group glycosyltransferases. The H enzyme could not be detected using either type 1 or type 2 chain acceptors. The B enzyme was present in normal amount when 2'-fucosyllactose was used as substrate, neither 6'-fucosyllactose nor 6'-fucosyllactosamine could act as acceptors for the B enzyme. Upon treatment of the Bh red cells by the B-degrading enzyme from Trichomonas foetus the B antigen was destroyed while H determinants were uncovered (B-H + cells). The cells thus treated could be further converted into A&H-red cells by the action of the A transferase from human blood group A serum. Previous treatment of the B-H + cells by the H-degrading enzyme from T. foetus, however, led to B-/-erythrocytes and prevented their conversion into A red blood cells by the A enzyme. The results clearly demonstrate that, as found in normal B individuals, the B antigen from Bh cells is built up from the H precursor and provide additional evidence that H is not a completely silent gene in Bh individuals.

ABO Blood-Group System↗
PubMed1977

Bromopyruvate as an affinity label for baker's yeast flavocytochrome b2. Kinetic study of the inactivation reaction.

Bromopyruvate was shown to completely inactivate cytochrome b2 in a reaction that obeyed the kinetic criteria required for affinity labels: it inactivated flavocytochrome b2 according to saturation kinetics, and the inactivation reaction was competitively inhibited by the substrate or competitive inhibitors. Inactivation was irreversible. The behaviour of both forms of flavocytochrome b2 (lintact and proteolytically cleaved) was examined. It was found that the reduced cleaved enzyme was not inactivated by bromopyruvate; this phenomenon can probably be ascribed to a structural change undergone upon reduction. The value of the lactate dissociation constant of intact cytochrome b2 cytochrome b2 was determined in competition experiments with bromopyruvate. By comparison with the divergent published values for the Ks of the cleaved from, it appears that only those that differ from the Km by a factor of two or three are reasonable. This study opens the way for the identification of an active site residue and localization in the peptide chain of the bifunctional enzyme.

Affinity Labels↗