Prothymosin alpha is processed to thymosin alpha 1 and thymosin alpha 11 by a lysosomal asparaginyl endopeptidase.

Sarandeses CS, Covelo G, Díaz-Jullien C, Freire M

The Journal of biological chemistry28 Jan 2003Cited by 60 (Europe PMC)

PMID12554742DOI10.1074/jbc.m213005200PepBankPUB-12554742

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Summary

Thymosin alpha(1) (T alpha(1)) and thymosin T alpha(11) (T alpha(11)) are polypeptides with immunoregulatory properties first isolated from thymic extracts, corresponding to the first 28 and 35 amino acid residues, respectively, of prothymosin alpha (ProT alpha), a protein involved in chromatin remodeling. It has been widely supposed that these polypeptides are not natural products of the in vivo processing of ProT alpha, since neither was found in extracts in which proteolysis was prevented. Here we show that a lysosomal asparaginyl endopeptidase is able to process ProT alpha to generate T alpha(1) and T alpha(11). In view of its catalytic properties and structural and immunological analyses, this protease was identified as mammalian legumain. It selectively cleaves some of the asparaginyl-glycine residues in the ProT alpha sequence; specifically, Asn(28)-Gly(29) and Asn(35)-Gly(36) residues are cleaved with similar efficiency in vitro to generate T alpha(1) and T alpha(11), respectively. By contrast T alpha(1) is the main product detected in vivo, free in the cytosol, at concentrations similar to that of ProT alpha. The data here reported demonstrate that T alpha(1) is not an artifact but rather is naturally present in diverse mammalian tissues and raise the possibility that it has a functional role.

CC BYText from Europe PMC. Highlighted sentences are the source of results.

Results from this study2

No result from this study comes from a test of the peptide.

Natural levels measured1

These results measure the body's own peptide. Nobody was given the peptide. They are not evidence about taking it. They are left out of key results, evidence counts and charts.

01LabEndogenous levelEx vivo tissueOther
In mammalian tissues, thymosin alpha‑1 is naturally present, free in the cytosol, at concentrations similar to prothymosin alpha.
In plain wordsIn lab tests on mammalian tissue, the body's own thymosin alpha‑1 was found free in the cell fluid.
Peptide
Thymosin alpha-1
Outcome
Not applicablePresence of natural thymosin alpha 1 in mammalian tissue
Study
mammaliann: not reported in source
mammalian tissues
Outcome group
Immune response · Immune and inflammation
Source sentences
Summary
By contrast T alpha(1) is the main product detected in vivo, free in the cytosol, at concentrations similar to that of ProT alpha.
2 context sentences(design, population, supporting numbers)
Summary · context
The data here reported demonstrate that T alpha(1) is not an artifact but rather is naturally present in diverse mammalian tissues and raise the possibility that it has a functional role.
Summary · context
Here we show that a lysosomal asparaginyl endopeptidase is able to process ProT alpha to generate T alpha(1) and T alpha(11).
This result measures the body's own Thymosin alpha-1. Nobody was given the peptide. It is not evidence about taking it.
Show in the study text Report a problemFND-1255474202

Studies that did not test the peptide alone1

In this study, Thymosin alpha-1 was a lab tool or a carrier, part of a mix, or the subject of a lab method. These results are not evidence about taking Thymosin alpha-1.

02LabNot a test of Thymosin alpha-1 aloneIn vitro (cell-free)Mechanism
In vitro, legumain cleaved prothymosin alpha at Asn28-Gly29 and Asn35-Gly36 with similar efficiency to generate thymosin alpha‑1 and thymosin alpha 11.
In plain wordsIn lab tests, an enzyme called legumain cut prothymosin alpha to make thymosin alpha‑1 and thymosin alpha 11.
Peptide
Thymosin alpha-1
Outcome
Not applicableCleavage of prothymosin alpha by legumain to thymosin alpha 1 and alpha 11
Study
n: not reported in source
lysosomal asparaginyl endopeptidase (mammalian legumain) with prothymosin alpha in vitro
Outcome group
Receptor activity and mechanism · Pharmacology
Source sentences
Summary
It selectively cleaves some of the asparaginyl-glycine residues in the ProT alpha sequence; specifically, Asn(28)-Gly(29) and Asn(35)-Gly(36) residues are cleaved with similar efficiency in vitro to generate T alpha(1) and T alpha(11), respectively.
1 context sentence(design, population, supporting numbers)
Summary · context
Here we show that a lysosomal asparaginyl endopeptidase is able to process ProT alpha to generate T alpha(1) and T alpha(11).
In this study, Thymosin alpha-1 was a lab tool or a carrier, part of a mix, or the subject of a lab method. This result is not evidence about taking Thymosin alpha-1.
Show in the study text Report a problemFND-1255474201

AI wrote and checked these results. AI can make mistakes, so check important results against the source.

Version history

PepBank keeps every version of the data on this study. Status changes from Retraction Watch, Europe PMC and Crossref are listed with their source.

Version 3Current
10 Oct 2026, 08:55 UTC
Study results updated
Version 2
9 Oct 2026, 03:03 UTC
Study data updated · source update from Europe PMC
Version 1
9 Oct 2026, 03:02 UTC
First added · source update from Europe PMC

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