title: Thymosin beta 4Xen: a new thymosin beta 4-like peptide in oocytes of Xenopus laevis.
abstract: Two new thymosin beta 4-like peptides have been detected in ovaries of Xenopus laevis and Rana esculenta. Previously, it was reported that thymosin beta 4 can be found in various species, from mammals to amphibians, e.g., in X. laevis [S. Erickson-Viitanen, S. Ruggieri, P. Natalini, and B.L. Horecker (1983) Arch. Biochem. Biophys. 221, 570-576]. However, oocytes and spleen from R. esculenta contain no thymosin beta 4 but a similar peptide without methionine. The peptide from R. esculenta elutes from a reversed-phase column about 5 min later than thymosin beta 4. The peptide from X. laevis, referred to as thymosin beta 4Xen, can hardly be distinguished from thymosin beta 4 by its retention time on HPLC, by amino acid analysis, its isoelectric point, or tryptic fingerprinting. Amino acid analyses of the tryptic fragments, however, have revealed that thymosin beta 4 and beta 4Xen are different. The amino acid sequence of thymosin beta 4Xen is reported. Thymosin beta 4 and beta 4Xen differ in the amino acid residues at positions 15, 40, and 41. At position 15 serine is replaced by alanine and at 41-42 the sequence is Thr-Ser instead of Ala-Gly. Depending on their size, defolliculated oocytes contain between 2.7 and 52.6 ng thymosin beta 4Xen which is comparable to the amount of histones in oocytes.
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D005260:Female; D005998:Glycine / Q000032:analysis; D007526:Isoelectric Point; D008969:Molecular Sequence Data; D009865:Oocytes / Q000032:analysis*; D010446:Peptide Fragments / Q000032:analysis; D013912:Threonine / Q000032:analysis; D013947:Thymosin / Q000031:analogs & derivatives* / Q000032:analysis; D014018:Tissue Distribution; D014357:Trypsin / Q000378:metabolism; D014982:Xenopus laevis; D000099201:Thymosin beta(4)
chemical_list: D000596:Amino Acids; D005998:Glycine; D010446:Peptide Fragments; D013912:Threonine; D013947:Thymosin; D014357:Trypsin; D000099201:Thymosin beta(4)