The eucaryotic cells possess specific intracellular transport system to deliver newly synthesized proteins to their sites of function. This review summarizes the biosynthetic protein transport pathways and highlights the recent progress in the studies of mitochondrial protein import.
The catalytic mechanism of E. coli aspartate aminotransferase was studied by the sitespesific mutagenesis and physicochemical methods. The amino acid residues in the active site were mutated. The mutated enzymes were overproduced and purified. The enzymecatalyzed transamination reaction is consisted of several steps. We identified some residues responsible for each reaction step.
Three functionally important sites of myosin head, i.e. ATPase site, actin-binding site and SH1 thiol, were identified in its three-dimensional structure by electron microscopy. These sites were also mapped along primary structures of myosin heavy and light chains by chemical methods such as affinity labeling, chemical crosslinking and "end-label fingerprinting".
The family relationships among a sample of members drawn from a particular generation of populations or species play a central role in describing the genealogical behaviour of generations of individuals. Such a genealogical approach is certainly interesting and important in its own right, but it is also very useful to produce a wide variety of classical results in the mathematical theory of population genetics. The power and elegance of the theory rely on 'equivalence' or 'exchangeability' among individuals in a population and have been best demonstrated in single-locus multiple-allele systems. Here I would like to introduce the basic idea of the theory and some results of its application to molecular taxonomy.
Two types of hypermodification of uridine in the first position of the anticodon of tRNAs make the conformation of this residue very rigid or very flexible, which contribute to the correct and efficient recognition of codons by tRNAs in protein biosynthesis according to the genetic code.
Effects of buffering agent on transmembrane flux of H+/OH- are theoretically examined for the kinetic analysis of intravesicular pH relaxation experiments. Methods for determining H+/OH- permeabilities are shown to have revealed new aspects in the transmembrane H+/OH- movement, i.e., involvement of buffering and conduction on the membrane surface.