Human prothymosin α: Amino acid sequence and immunologic properties

Pan, Luxing; Haritos, A.A.; Wideman, Janusz; Komiyama, Tomoyoshi; Chang, May; Stein, Stanley J.; Salvin, S. B.; Horecker, B.L.

doi:10.1016/0003-9861(86)90717-4

Cited by 89 publications

(62 citation statements)

References 6 publications

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“…Synthetic thymosin a1 was provided by A. Felix (Roche Research Center, Nutley, NJ). Prothymosin a was isolated from fresh-frozen rat or human thymus (17,24). Fluorescamine was obtained from HoffmannLa Roche.…”

Section: Methodsmentioning

confidence: 99%

Prothymosin alpha in human blood.

Panneerselvam¹,

Haritos²,

Caldarella³

et al. 1987

Proc. Natl. Acad. Sci. U.S.A.

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The major cross-reacting peptide in human plasma detected with a radioimmunoassay (RIA) for thymosin a, was identified as prothymosin a, based on its elution properties in gel-filtration chromatography and its amino acid composition after purification by HPLC. A small quantity (<10%) of the total cross-reacting material was recovered in fractions corresponding to lower molecular weight thymosin al-like peptides. The total quantity of cross-reacting material detected in human blood, expressed as thymosin a, equivalents, was 11-14 pmol/ml (-90% was recovered in the leukocyte fraction, =10% was in the plasma fraction, and 1-2% was in the erythrocyte fraction). The peptide present in leukocytes was also identified as prothymosin a. After correction for the 5-times lower molar reactivity of prothymosin a in the thymosin a, RIA employed in these experiments, we estimate that the content of prothymosin a in human blood is 55-70 pmol/ml (0.6-0.8 pg/ml). The relatively small quantities recovered in the erythrocyte and plasma fractions may be attributed to contamination of the former by leukocytes or to leakage from leukocytes into the plasma.Thymosin a1, an acidic peptide containing 28 amino acid residues (1), was first isolated from a calf thymus preparation called thymosin fraction 5, a biologically active mixture of peptides ranging in molecular weight from 1000 to 15,000 (2). Thymosin a1 has been reported not only to be active in several assay systems for enhancement of immune function, both in vitro and in vivo, but also to be much more potent than the thymosin fraction 5 preparations from which it was isolated (for reviews, see refs. 3-5).Radioimmunoassays (RIAs) for thymosin a1 have been developed in several laboratories (6)(7)(8)25) and employed for the analysis of cross-reacting material in serum or plasma (6, 9-12). Highest levels of immunoreactive peptides were found in cord plasma (6), but detectable quantities (0.6-3.7 ng of thymosin a1 equivalents per ml) were also present in the serum of adolescents (6) or normal adults (12). Of particular interest were reports that the levels of immunoreactive thymosin a,-like material were elevated in serum from patients with acquired immunodeficiency syndrome and also in a group of homosexual men (13,14). Another report, however, suggests that the high levels in serum from patients with acquired immunodeficiency syndrome may be due to the presence of a product of the gag gene of human immunodeficiency virus, which contains an amino acid sequence homologous to the sequence in thymosin a1 that was recognized by the antibody employed (15). This antiserum was also reported to block the replication of human immunodeficiency virus in permissive H9 cells (15).The identity and possible origin of the cross-reacting material in normal blood have not yet been established. A cross-reacting peptide purified from a preparation of Cohn fraction IV-1 by immunoaffinity chromatography was reported to resemble thymosin a1 in size and chromatographic properties (16). However, the i...

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Section: Methodsmentioning

confidence: 99%

Prothymosin alpha in human blood.

Panneerselvam¹,

Haritos²,

Caldarella³

et al. 1987

Proc. Natl. Acad. Sci. U.S.A.

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“…Although the function of prothymosin ␣ has not been elucidated, its structure may provide clues. The major form of the human protein has 109 amino acids, 53 of which are acidic (24,28,37,38,44). It is devoid of tyrosine, tryptophan, phenylalanine, histidine, methionine, and cysteine, with leucine, isoleucine, and proline residues occurring at only one location.…”

mentioning

confidence: 99%

Do Products of the myc Proto-Oncogene Play a Role in Transcriptional Regulation of the Prothymosin α Gene?

Mol

Wang

Batey

et al. 1995

Molecular and Cellular Biology

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The Myc protein has been reported to activate transcription of the rat prothymosin ␣ gene by binding to an enhancer element or E box (CACGTG) located in the first intron (S. Gaubatz et al., Mol. Cell. Biol. 14:3853-3862, 1994). The human prothymosin ␣ gene contains two such motifs: in the promoter region at kb ؊1.2 and in intron 1, ϳ2 kb downstream of the transcriptional start site in a region which otherwise bears little homology to the rat gene. Using chloramphenicol acetyltransferase (CAT) reporter constructs driven either by the 5-kb human prothymosin ␣ promoter or by a series of truncated promoters, we showed that removal of the E-box sequence had no effect on transient expression of CAT activity in mouse L cells. When intron 1 of the prothymosin ␣ gene was inserted into the most extensive promoter construct downstream of the CAT coding region, a diminution in transcription, which remained virtually unchanged upon disruption of the E boxes, was observed. CAT constructs driven by the native prothymosin ␣ promoter or the native promoter and intron were indifferent to Myc; equivalent CAT activity was observed in the presence of ectopic normal or mutant Myc genes. Similarly, expression of a transiently transfected wild-type prothymosin ␣ gene as the reporter was not affected by a repertoire of myc-derived genes, including myc itself and dominant or recessive negative myc mutants. In COS-1 cells, equivalent amounts of the protein were produced from transfected prothymosin ␣ genes regardless of whether genomic E boxes were disrupted, intron 1 was removed, or a repertoire of myc-derived genes was included in the transfection cocktail. More importantly, cotransfection of a dominant negative Max gene failed to reduce transcription of the endogenous prothymosin ␣ gene in COS cells or the wild-type transfected gene in COS or L cells. Taken together, the data do not support the idea that Myc activates transcription of the intact human prothymosin ␣ gene or reporter constructs that mimic its structure. Rather, they suggest that the human prothymosin ␣ promoter and downstream elements are buffered so as to respond poorly, if at all, to transient fluctuations in transcription factors which regulate other genes.

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“…Prothymosin a consists of 109-11 1 amino acid residues, with an acidic region of aspartic acid and glutamic acid residues in the centre of the molecule (Goodall et al, 1986;Eschenfeldt and Berger, 1986;FrangouLazaridis et al, 1988). Intact protein has been isolated from a number of species, and lymphoid tissues were found to contain the highest levels of protein and mRNA (Haritos et al, 1984b;Pan et al, 1986;Economou et al, 1988;Clinton et al, 1989;Dosil et al, 1990;Frillingos et al, 1991).…”

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confidence: 99%

Regulation of Prothymosin α During the Cell Cycle

Vareli

Tsolas

Frangou-Lazaridis

1996

European Journal of Biochemistry

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A number of studies have indicated that the small nuclear acidic protein prothymosin a is associated with cellular-proliferation events. For example, c-myc causes immediate transcriptional activation of prothymosin a, and prothymosin a antisense oligonucleotides inhibit myeloma cell division.To investigate the regulation of prothymosin a, we examined its mRNA and protein levels during the cell cycle of mononuclear cells and fibroblastic cells. We isolated immunoreactive material from cellular extracts and immunolocalized the protein to the nucleus during the cell cycle. We report here that the material present in the cells is prothymosin a rather than the amino-terminal peptide thymosin 01.['HIThymidine-incorporation studies associate maximum accumulation of mRNA and protein with the S/G2 phase of the cell cycle. This induction of prothymosin a mRNA seems to resemble cyclin B expression and is more pronounced in fibroblasts. Moreover, transient-transfection experiments indicate that transcription factor E2F is a strong positive regulator of the prothymosin a gene. Our results are consistent with the hypothesis that prothymosin a is involved in proliferation checkpoints of the cell cycle.

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Human prothymosin α: Amino acid sequence and immunologic properties

Cited by 89 publications

References 6 publications

Prothymosin alpha in human blood.

Prothymosin alpha in human blood.

Do Products of the myc Proto-Oncogene Play a Role in Transcriptional Regulation of the Prothymosin α Gene?

Regulation of Prothymosin α During the Cell Cycle

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