The complete sequences of trout (Salmo gairdneri) thymosin β11 and its homologue thymosin β12

Abstract

Two forms of beta-thymosins, designated thymosin beta 11 and thymosin beta 12, were isolated from trout (Salmo gairdneri) spleen. This suggests that the presence of two beta-thymosins, previously thought to be a property of mammalian tissues only, is a more general phenomenon in vertebrate species. Both trout beta-thymosins were found to be N-terminally blocked by a group identified as acetyl by m.s. Automated protein sequencing of tryptic, thermolytic and Staphylococcus aureus in 41-residue V8 proteinase fragments revealed that one of the two beta-thymosins corresponds to the previously reported 41-residue-long sequence of thymosin beta 11 with two substitutions at positions 5 and 7, i.e. Asn instead of Asp, and Glu instead of Gln, whereas the other beta-thymosin, designated thymosin beta 12, was found to be a 42-residue polypeptide closely similar in sequence to thymosin beta 11, with five substitutions (i.e. at positions 5, 7, 10, 11 and 41, with Asp, Ala, Ser, Asn and Thr instead of Asn, Glu, Ala, Ser and Ser respectively) and one addition at position 42 (Ala). Comparison of the known six sequences of beta-thymosins together with the sequences reported here showed that the sequence similarity of the two beta-thymosins in trout (86%) is greater than that of the two beta-thymosins in mammalian species (74%) and that residues at 28 positions are identical in all beta-thymosins, the longer conserved segments located at positions 16-26 and 31-38.

Identification and characterization of homologues of vertebrate β‐thymosin in the marine mollusk Aplysia californica

“… Sequence alignments of two novel Aplysia β‐thymosin isoforms and related thymosin proteins from different species (GenPept sea urchin, AAC26833; rainbow trout, P26352; perch, AAB21004; and chick, AAQ55552.1); confirmed acetylated residues are indicated 35, 37, 38. Translated sequence of the chick β 4 thymosin contains priming methionine.…”

A novel β-thymosin from the sea urchin: extending the phylogenetic distribution of β-thymosins from mammals to echinoderms

“…Comparing the primary sequences of all known b-thymosins, including that of the sea urchin, it is striking that they all have a tripeptide sequence (2±4) as a common structural element and it could be postulated that this segment is responsible for the second functional entity. The high homology of the b-thymosins throughout the animal kingdom (Figure 8), and especially the conserved segments DKP (2±4) and LKKTET (17± T b4 : human, chicken, cat [11], calf [1], rat, mouse [5], gecko [13], horse [31], whale [32], guinea pig [33], pig, ovine, murine [34] T b4ala : rabbit [11] T b4xen : xenopus laevis [9] T b9 : calf [8] T b9met : calf [8] T b9met : pig [10,16] T b10 : human, cat, rat, mouse [12], rabbit [14], horse [31] x T b11 : trout [13,15] T b12 : trout [15] xx T b12p : perch [35] xx T b13 : whale [32] T b14 : sea urchin (from this study) x T b10 : in the original sequencing studies of Erickson-Viitanen et al [12] arginine-39 is missing. However, subsequent studies [36] indicated that thymosin b 10 has 43 amino acid residues including arginine 39 xx T b12 and T b12p : from trout spleen, T b11 and T b12 were isolated in 1992 [15].…”

“…The thymosin b 14 fragments thus isolated were characterized by amino acid analysis and sequencing (Table 2 and Figure 5). On the basis of the combined interpretation of the value for the molecular mass of fraction 1±4, its amino acid composition and the homology to the known structures of other bthymosins (b 4 [1], b 9 [8], b 11 and b 12 [15]), the Nterminal sequence of thymosin b 14 was deduced to be Ac-Ser-Asp-Lys-Pro ( Figure 5). To confirm the sequence of the first four residues a synthetic Although fraction AIV (fragment 13±40) served as overlap for residues 23±24, tryptic digestion was used to confirm the amino acid sequence of thymosin b 14 derived from the Asp-N fragments.…”

C‐terminal truncation of thymosin β10 by an intracellular protease and its influence on the interaction with G‐actin studied by ultrafiltration

“…Most recently a third β‐thymosin (β 15 ) has been detected in Dunning rat prostate carcinoma additionally to thymosin β 4 and β 10 [13]. In tissues of rabbit [7, 14] and trout [15, 16] two β‐thymosins are found in comparable concentrations. Rabbit spleen contains thymosin β 4 Ala and β 10 whereas in the spleen of trout thymosin β 11 and β 12 ‐trout are present.…”