TY - JOUR TI - The identification of prothymosin α-like material in vertebrate lymphoid organs by a radioimmunoassay for the N-terminal decapeptide AU - Yialouris, P.P. AU - Evangelatos, G.P. AU - Soteriadis-Vlahos, C. AU - Heimer, E.P. AU - Felix, A.M. AU - Tsitsiloni, O.E. AU - Haritos, A.A. JO - Journal of Immunological Methods PY - 1988 VL - 106 TODO - 2 SP - 267-275 PB - SN - 0022-1759 TODO - 10.1016/0022-1759(88)90207-4 TODO - prothymosin alpha; thymosin alpha1, animal cell; cattle; chicken; fish; lymphoid organ; methodology; priority journal; radioimmunoassay; vertebrate, Animal; Binding, Competitive; Cattle; Chickens; Lymphoid Tissue; Oligopeptides; Protein Precursors; Radioimmunoassay; Structure-Activity Relationship; Support, Non-U.S. Gov't; Thymosin; Trout TODO - A radioimmunoassay (RIA) is described for the detection and quantitation of prothymosin α (ProT α), and its N-terminal fragments containing as a minimum the first ten amino acid residues. This range of peptides includes thymosins α1 (T α1) and α11 (T α11). Antibodies against T α1 and the tracerα1(1-10)Tyr11(125I), an analogue of the major epitope, were utilized in this RIA. 50% displacement of the ligand was observed with 1.3 pmol of T α1 and 6.4 pmol of ProT α. The partially homologous parathymosin α (ParaT α) showed less than 2% crossreactivity with ProT A. Sephacryl S-200 gel filtration separation of the peptides of calf thymus, chicken spleen and trout spleen extracts prepared by a method eliminating proteolysis, combined with the above RIA, showed the presence of a major immunoreactive peak. Its elution volume corresponded to that of rat ProT α (apparent mol. weight 36000) for both calf (37000) and chicken (35000) tissues. In trout it corresponded to a significantly higher molecular weight (62000). No detectable levels of shorter fragments, including T α1, were observed in any of the above species. The levels of ProT α-like peptides in calf thymus, chicken spleen and trout spleen were found to be 246, 8.6 and 7.7 μg respectively, of rat ProT α equivalents per gram of fresh tissue. The significance of the presence of ProT α-like polypeptides in vertebrate species as distant as fish and mammals, the absence of short T α1-like fragments, and the relative conservation of the N-terminus as suggested by the RIA is discussed. © 1988. ER -