Spectrophotometric titration of pyridoxamine-pyruvate transaminase (EC 2.6.1.30) with pyridoxal at pH 7.15 gives four equivalent binding sites per tetramer. The pH dependence of the equilibrium constant for the association of 5'-deoxypyridoxal with the active site lysine residue was determined spectrophotometrically. These dissociation constants increase with increasing pH over the range pH 7.5...

The TCR is a complex receptor composed of seven polypeptide chains consisting of a ligand-binding subunit, Ti, and a putative signal-transducing subunit, CD3. Phylogenetically conserved charged amino acid residues within the membrane-spanning domains present in all seven chains of the TCR have been proposed to be important in the association between Ti and CD3. Using a Ti beta chain-deficient m...

Lysine is considered an 'essential amino acid' required at sufficient levels to prevent malnutrition and serious diseases, particularly in developing countries. It is mostly obtained from various plant foods. In the current issue (pages 4285–4296) Yang and colleagues report on successful stimulation of lysine biosynthesis and suppression of its catabolism in transgenic rice plants without chang...

The protein known as eIF5A (eukaryotic initiation factor 5A) has an elusive role in translation. It has a unique and essential hypusine modification at a conserved lysine residue in most eukaryotes. In addition, this protein is modified by phosphorylation with unknown functions. In the present study we show that a phosphorylated state of eIF5A predominates in exponentially growing Trypanosoma c...

The T-lymphocyte proliferative response to pigeon cytochrome c was studied in the mouse. H-2a and H-2k strains were responders to this antigen whereas H-2b, H-2d, H-2f, H-2ja, H-2p, H-2q, H-2r, H-2s, and H-2u strains were low or nonresponders. Genetic mapping demonstrated that two major histocompatibility complex (MHC)-linked Ir genes control the response, one in I-A, the other in I-E/I-C. The ...

The DevR (DosR) response regulator initiates the bacterial adaptive response to a variety of signals, including hypoxia in in vitro models of dormancy. Its receiver domain works as a phosphorylation-mediated switch to activate the DNA binding property of its output domain. Receiver domains are characterized by the presence of several highly conserved residues, and these sequence features correl...

Helix formation in a 17-residue alanine-lysine peptide and analogous peptides with specific lysine --> X substitutions, where X is 2,3-diamino-L-propionic acid, 2, 4-diamino-L-butyric acid or L-ornithine, have been examined using circular dichroism measurements. The dependence of helix content on X, its position in the sequence, and the number of lysine --> X substitutions are reasonably well d...