M Selg | PubMed Health

PubMed2001

Numerically complemented analytic method for solving the time-independent one-dimensional Schrödinger equation.

A general method of solving the one-dimensional Schrödinger equation is developed. The first step is to construct an exactly solvable reference potential of several smoothly joined Morse-type components, which should be a good approximation to a given potential. The exact solutions for that reference Hamiltonian are then combined with a nonperturbative approach [R. G. Gordon, J. Chem. Phys. 51, 14 (1969)], which enables us to numerically solve the energy eigenvalue problem for the original potential to any desired accuracy. A full description of the analytical procedures is given and examples of both exact and numerical solutions, are presented.

Journal Article↗

PubMed1997

Cloning and characterization of HUPF1, a human homolog of the Saccharomyces cerevisiae nonsense mRNA-reducing UPF1 protein.

Levels of most nonsense mRNAs are normally reduced in prokaryotes and eukaryotes when compared with that of corresponding functional mRNAs. Genes encoding polypeptides that selectively reduce levels of nonsense mRNA have so far only been identified in simple eukaryotes. We have now cloned a human cDNA whose deduced amino acid sequence shows the highest degree of homology to that of UPF1, a bona fide Saccharomyces cerevisiae group I RNA helicase required for accelerated degradation of nonsense mRNA. Based on the total sequence of the shorter yeast UPF1 protein, the overall identity between the human protein and UPF1 is 51%. Besides NTPase and other RNA helicase consensus motifs, UPF1 and its human homolog also share similar putative zinc finger motifs that are absent in other group I RNA helicases. Northern blot analysis with the human cDNA probe revealed two transcripts in several human cell lines. Further, antibodies raised against a synthetic peptide of the human polypeptide detected a single 130 kDa polypeptide on Western blots from human and mouse cells. Finally, immunofluorescence and Western blot analyses revealed that the human and mouse polypeptides, like yeast UPF1, are expressed in the cytoplasm, but not in the nucleus. We have thus identified the first mammalian homolog of yeast UPF1, a protein that regulates levels of nonsense mRNA, and we tentatively name this protein human HUPF1 (for human homolog of UPF1).

Amino Acid Sequence↗