Isolation and partial sequence of goat spleen prothymosin ?

Frillingos, Stathis; Frangou-Lazaridis, Maria; Seferiadis, K.; Hulmes, Jeffrey D.; Pan, Yu; Tsolas, O.

doi:10.1007/bf00239545

Cited by 31 publications

(31 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The primary structures of ProT~z from diverse animal tissues are extremely similar [2], suggesting a high degree of conservation in the course of evolution.…”

Section: Prothymosin a Is A 125 Kda Acidic Polypeptide That Inelttdementioning

confidence: 99%

“…Reports concerning the involvement ofcasein kinase-2, a Ser/Thr kinase using both ~'I'P and ATP as phosphate donors [11], in the phosphorylation of high-mobility group proteins [12] and in protein transport between the nucleus and cytoplasm [13], led us to realize that ProT0t from calf thymus and other sources [2] has three sites that are suitable for phosphorylation by CK-2, two at the N-terminus and one at the C-terminus (see the calf thymocyte ProT0~ sequence shown in Fig. I).…”

Section: Prothymosin a Is A 125 Kda Acidic Polypeptide That Inelttdementioning

confidence: 99%

See 1 more Smart Citation

Prothymosin α is phosphorylated by casein kinase‐2

Barcia¹,

Castro²,

Jullien³

et al. 1992

FEBS Letters

View full text Add to dashboard Cite

Prothymosin ~z (ProTg) is a 12.5 kDa acidic polypeptide that is considered to have a nuclear function related to cell proliferation. Inspection of its amino acid sequence revealed the presence of sequences that may serve as targets for phosphorylation by casein kinase-2 (CK-2). ProT~ isolated from calf thymocytes was phosphorylated in vitro by CK-2. The phosphc..~'iation sites are Ser and Thr residues located among the first 14 amino acid residues in the ProTa sequence. Another site that is theoretically suitable/'or phosphorylation by CK-2, at the C-terminus of the polypeptide, is not, in fact, phosphorylated. Thymosin cz~ (T~t), a peptide whose sequen~ corresponds to the first 28 amil~o acids of ProT~, is also phosphorylated by CK-2 at the same phosphorylation sites as ProT~e. In cultured splenic lymphocytes ProTg was phosphorylated at Thr residues located at positions 7, 12 and/or 13. Based on these observations we conclude that CK-2, or another celh,lar kinase with similar sequence specifity, is responsible for phosphorylation of ProTg in vivo.Prothymosin 0~; Thymosin r,;,; Casein kinase.2

show abstract

“…The primary structures of ProT~z from diverse animal tissues are extremely similar [2], suggesting a high degree of conservation in the course of evolution.…”

Section: Prothymosin a Is A 125 Kda Acidic Polypeptide That Inelttdementioning

confidence: 99%

Section: Prothymosin a Is A 125 Kda Acidic Polypeptide That Inelttdementioning

confidence: 99%

Prothymosin α is phosphorylated by casein kinase‐2

Barcia¹,

Castro²,

Jullien³

et al. 1992

FEBS Letters

View full text Add to dashboard Cite

show abstract

“…The second study of phosphoprothymosin ␣, a much less exhaustive analysis in mouse splenic lymphocytes, placed the labeled phosphate(s) on unspecified threonine residue(s) near the N terminus (22). Because prothymosin ␣ sequences from different species are nearly identical, with ϳ95% sequence homology over the entire protein and 100% sequence homology within the amino-terminal 30 residues (23,24), the discrepancy was unsettling.…”

mentioning

confidence: 99%

Prothymosin α in Vivo Contains Phosphorylated Glutamic Acid Residues

Trumbore

Wang

Enkemann

et al. 1997

Journal of Biological Chemistry

View full text Add to dashboard Cite

2) Immediately upon cell lysis, the pH stability curves of metabolically labeled native [ 32 P]prothymosin ␣ or a [ 32 P]histidine-tagged variant resembled the pH stability curve of acetyl phosphate. 3) After a brief incubation at pH 7, these curves changed from a pattern diagnostic for an acyl phosphate to that characteristic of a serine or threonine phosphate, an observation consistent with transfer of phosphate in vitro. Our data indicate that most of prothymosin ␣'s phosphates are subject instantaneously to hydrolysis, based on the observation that greater than 90% of the phosphate initially found at pH 7 disappeared at the extremes of pH. Rapid loss of phosphate was not affected by the presence of phosphatase inhibitors including 50 mM sodium fluoride, 1 mM okadaic acid, and 0.5 mM calyculin A. The amount of phosphate missing could not be ascertained, but the trifling amount recovered on Ser or Thr depended heavily on conditions favoring the transient survival of labile phosphate. Further analysis using COS cells lysed in the presence of sodium borohydride showed that: 1) phosphate recovered on prothymosin ␣ decreased 8-fold when lysates were treated with borohydride; 2) the reagent caused 4 -8 glutamic acid residues/molecule to vanish; 3) using [ 3 H]NaBH 4 , label was introduced into proline, a product derived from reductive cleavage of phosphoglutamate; and 4) [ 3 H]proline was localized almost exclusively to a peptide with pronounced homology to the histone binding site of nucleoplasmin, a chromatin remodeling protein found in Xenopus laevis. Our data demonstrate that prothymosin ␣ is energy-rich by virtue of stoichiometric amounts of glutamyl phosphate.Prothymosin ␣ is a highly unusual protein with an unfortunate name. The protein is neither a precursor for processed polypeptides nor specifically associated with the thymus nor a member of a family with ␤ or ␥ homologues (1-3). Instead, it is probably the most acidic naturally occurring polypeptide in the eukaryotic world, with 54 carboxyl groups in 109 amino acids, resulting in an isoelectric point at or below pH 3.5 (1, 2, 4). The mRNA for prothymosin ␣ is distributed ubiquitously among mammalian nucleated cells and tissues (1). The protein possesses a potent nuclear localization signal and is present in amounts equivalent to those of histone H1 (5, 6). Because the amount of prothymosin ␣ mRNA (and presumably protein) found in a cell is directly proportional to cell growth, the protein is believed to play a role in cell proliferation (1). This idea was reinforced by the observation that synchronized human myeloma cells, in the presence of antisense oligodeoxyribonucleotides directed at prothymosin ␣ mRNA, were unable to divide while detectable amounts of the antisense oligonucleotides remained inside the cell (7). There are now many examples of a link between prothymosin ␣ and growth in systems as diverse as developing mouse embryos (8); normal, mitogenstimulated, and malignant lymphocytes (9, 10); and regenerating liver (10). There are also positive ...

show abstract

“…Its sequence is highly conserved (5) and includes an extensive central acidic region (residues 41-85) comprised of Glu and Asp residues. Under physiological conditions, ProT␣ behaves as a monomeric protein with a random coil conformation (6,7).…”

mentioning

confidence: 99%

A 180-kDa Protein Kinase Seems to Be Responsible for the Phosphorylation of Prothymosin α Observed in Proliferating Cells

Pérez-Estévez

Díaz-Jullien

Covelo

et al. 1997

Journal of Biological Chemistry

View full text Add to dashboard Cite

Prothymosin ␣ (ProT␣) is an acidic protein involved in cell proliferation. Its phosphorylation status is correlated with proliferative activity. Here we report the isolation and characterization of a ProT␣-phosphorylating kinase (ProT␣K) from mouse splenocytes that seems to be responsible for the in vivo phosphorylation of ProT␣ and that differs from other protein kinases reported to date. This enzyme, mainly located in the cytosol, has an molecular mass of 180 kDa and appears to be made up of two proteins of 64 and 60 kDa. Its activity was markedly enhanced by mitogenic activation of cells. The ProT␣ residues phosphorylated by the enzyme in vitro are a Thr at position 7 and another Thr at positions 12 or 13, both located within casein kinase 2 (CK-2) consensus motifs; these are the same residues as are phosphorylated in vivo. The new enzyme shows a number of clear structural and catalytic differences from CK-2. It phosphorylates histones H2B and H3, although with weaker activity than ProT␣. An enzyme with the same characteristics was also found in other murine tissues and cell lines.

show abstract

Isolation and partial sequence of goat spleen prothymosin ?

Cited by 31 publications

References 31 publications

Prothymosin α is phosphorylated by casein kinase‐2

Prothymosin α is phosphorylated by casein kinase‐2

Prothymosin α in Vivo Contains Phosphorylated Glutamic Acid Residues

A 180-kDa Protein Kinase Seems to Be Responsible for the Phosphorylation of Prothymosin α Observed in Proliferating Cells

Contact Info

Product

Resources

About