Biomaterial Database

Translation initiation factor eIF-5A, the hypusine-containing protein, is phosphorylated on serine in Saccharomyces cerevisiae. 1993

H A Kang, and H G Schwelberger, and J W Hershey

Department of Biological Chemistry, School of Medicine, University of California, Davis 95616.

Translation initiation factor eIF-5A (formerly called eIF-4D) is a small, highly conserved protein in eukaryotic cells that undergoes a unique modification at one of its lysine residues to form hypusine. eIF-5A stimulates in vitro the synthesis of methionyl-puromycin, a model reaction for formation of the first peptide bond. In Saccharomyces cerevisiae eIF-5A is encoded by two highly homologous genes, TIF51A and TIF51B, and each gene gives rise to two hypusinated isoelectric variants, eIF-5Aa (more acidic) and eIF-5Ab (more basic). In order to study the structural and functional differences between the two isoforms, both isoelectric forms were purified from a yeast strain overexpressing TIF51A and were shown to stimulate identically the synthesis of methionyl-puromycin in a heterologous mammalian assay system. Pulse-chase labeling of yeast cells with [35S]methionine showed that the basic form, eIF-5Ab, is a precursor form of the acidic form, eIF-5Aa. Immunoprecipitation of 32P-labeled cell lysates with rabbit antibodies specific for yeast eIF-5A, phosphoprotein phosphatase treatment of eIF-5Aa, and phosphoamino acid analysis demonstrated that eIF-5Aa is generated by phosphorylation of eIF-5Ab on serine. Therefore eIF-5A undergoes two post-translational modifications, hypusination and phosphorylation, where the activity of the factor is dependent on the first but is not influenced in vitro by the second.

UI	MeSH Term	Description	Entries
D007525	Isoelectric Focusing	Electrophoresis in which a pH gradient is established in a gel medium and proteins migrate until they reach the site (or focus) at which the pH is equal to their isoelectric point.	Electrofocusing,Focusing, Isoelectric
D008239	Lysine	An essential amino acid. It is often added to animal feed.	Enisyl,L-Lysine,Lysine Acetate,Lysine Hydrochloride,Acetate, Lysine,L Lysine
D008969	Molecular Sequence Data	Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.	Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D010448	Peptide Initiation Factors	Protein factors uniquely required during the initiation phase of protein synthesis in GENETIC TRANSLATION.	Initiation Factors,Initiation Factor,Factors, Peptide Initiation,Initiation Factors, Peptide
D010766	Phosphorylation	The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.	Phosphorylations
D011233	Precipitin Tests	Serologic tests in which a positive reaction manifested by visible CHEMICAL PRECIPITATION occurs when a soluble ANTIGEN reacts with its precipitins, i.e., ANTIBODIES that can form a precipitate.	Precipitin Test,Test, Precipitin,Tests, Precipitin
D011498	Protein Precursors		Precursors, Protein
D011691	Puromycin	A cinnamamido ADENOSINE found in STREPTOMYCES alboniger. It inhibits protein synthesis by binding to RNA. It is an antineoplastic and antitrypanosomal agent and is used in research as an inhibitor of protein synthesis.	CL-13900,P-638,Puromycin Dihydrochloride,Puromycin Hydrochloride,Stylomycin,CL 13900,CL13900,P 638,P638
D004277	DNA, Single-Stranded	A single chain of deoxyribonucleotides that occurs in some bacteria and viruses. It usually exists as a covalently closed circle.	Single-Stranded DNA,DNA, Single Stranded,Single Stranded DNA
D005800	Genes, Fungal	The functional hereditary units of FUNGI.	Fungal Genes,Fungal Gene,Gene, Fungal