Type Of Beta Research Articles

Beta 0 thalassemia, a nonsense mutation in man.

We determined the complete nucleotide sequence of the 5' noncoding region and the first 74 amino acids of the nonfunctional beta-globin mRNA in a patient with homozygous beta 0 thalassemia. We identified the molecular defect as a single nucleotide substitution in the coding region of the mRNA. At the position corresponding to amino acid 17, replacement of an adenine by a uracil changes the triplet AAG, which codes for lysine in the normal beta chain, to an amber termination codon, UAG. This type of beta 0 thalassemia represents an example of a nonsense mutation in man.

B-2. VLDLからLDLへの中間体のうっ滞を示す高脂血症についての考察

B-2. VLDLからLDLへの中間体のうっ滞を示す高脂血症についての考察

Reconstitution of diphtheria toxin from two nontoxic cross-reacting mutant proteins.

The isolation of a new type of mutant Corynephage beta, which carries a missense mutation in the structural gene for diphtheria toxin synthesis is described. The lysogenic C7(8)(beta(197))(tox-crm+) strain of Corynebacterium diphtheriae produces a nontoxic, extracellular protein of molecular weight 62,000. This protein is immunologically indistinguishable from toxin itself but inhibits the action of toxin on HeLa cells, probably by competing for attachment sites on the cell membrane. In contrast to fragment A derived from diphtheria toxin, fragment A(197) is unable to catalyze the inactivation of eucaryotic polypeptidyl-transfer RNA-transferase II. When mixtures of the two nontoxic mutant proteins, enzymically active crm(45) protein and enzymically inactive crm(197) protein, are subjected to mild treatment with trypsin in the presence of a thiol and then allowed to reoxidize after dialysis to remove excess thiol, "diphtheria toxin" is reconstituted in high yield.