Cytoplasmic DNA-binding phosphoproteins of Physarum polycephalum

B. E. Magun

Research output: Contribution to journalArticle

4 Citations (Scopus)

Abstract

The cytoplasmic DNA-binding proteins of Physarum polycephalum were recovered by chromatography of cytosol extracts on sequential columns of native and denatured calf thymus DNA-cellulose. 5.4% of the total cytosol protein was bound to native DNA-cellulose, while 4.4% was bound to denatured DNA-cellulose. Stepwise salt gradient elution of the columns separated the DNA-binding proteins into 9 fractions which were analysed by acrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. Several hundred discrete polypeptide bands were identified, with many more high molecular weight polypeptides (greater than 100 000 D) binding to native than to denatured DNA. Continuous in vivo labelling of microplasmodia in KH2[32P]O4 and [3H]leucine was used to determine which of the DNA-binding proteins were phosphorylated, and to approximate their phosphorus content. About 30-40 phosphoproteins were resolved among the DNA-binding proteins. Most phosphoproteins contained less than 3 phosphates per polypeptide, but a small number of low molecular weight phosphoproteins (less than 50 000 D) contained from 5 to 10 phosphates per polypeptide. The majority of high molecular weight DNA-binding phosphoproteins bound to native DNA and were eluted with 0.25 M NaCl. As a group, the DNA-binding proteins were enriched in protein-bound phosphorus when compared with the cytosol proteins which did not bind to DNA. The phosphorus content of the cytoplasmic DNA-binding proteins was similar to that of the acidic nuclear proteins.

Original languageEnglish (US)
Pages (from-to)219-231
Number of pages13
JournalExperimental Cell Research
Volume103
Issue number1
DOIs
StatePublished - 1976
Externally publishedYes

Fingerprint

Physarum polycephalum
Phosphoproteins
DNA-Binding Proteins
DNA
Cytosol
Phosphorus
Peptides
Molecular Weight
Phosphates
Proteins
Acrylamide
Nuclear Proteins
Leucine
Sodium Dodecyl Sulfate
Electrophoresis
Chromatography
Salts
Gels
DNA-cellulose

ASJC Scopus subject areas

  • Cell Biology

Cite this

Cytoplasmic DNA-binding phosphoproteins of Physarum polycephalum. / Magun, B. E.

In: Experimental Cell Research, Vol. 103, No. 1, 1976, p. 219-231.

Research output: Contribution to journalArticle

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