ISSN:
1040-452X
Keywords:
Phosphorylation
;
Chromatin condensation
;
Testis
;
DNA binding proteins
;
Seminiferous tubules
;
Sonication-resistant nuclei
;
mP1
;
Pre-mP2
;
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Biology
Notes:
Mouse and rat seminiferous tubule fragment cultures were used to examine synthesis and processing of mammalian protamines and transition proteins. The tubule fragments were incubated with [3H]-arginine, [3H]-histidine, [35S]-cysteine, or [32P]-PO4, and radiolabeled proteins were analyzed by acid/urea polyacrylamide gel electrophoresis and fluorography or autoradiography. Newly synthesized protamines were recovered from sonication-resistant nuclei (SRN) and could not be detected in cytoplasmic fractions, indicating that protamines are deposited into nuclei immediately after synthesis. Newly synthesized mouse protamine 1 (mP1) and the precursor to mouse protamine 2 (pre-mP2) migrated more slowly during electrophoresis than their predominant testicular forms, identified by staining with Coomassie blue R-250. Within 1 hour of synthesis, the electrophoretic mobilities of mP1 and pre-mP2 increased to match those of their predominant forms. These changes are consistent with initial charge-neutralizing modifications of the newly synthesized protamines, followed by removal of at least some of the modifying ligands, to unmask protamine basicity. Steady-state phosphorylation rates were high for rat protamine 1 (rP1) and were independent of phosphate content; both rP1 molecules of low and high phosphate content were rapidly phosphorylated. Pre-mP2-3, a major processing intermediate derived by proteolysis of pre-mP2, was also rapidly phosphorylated. Like the protamines, transition protein 2 (TP2) was rapidly phosphorylated and increased in electrophoretic mobility soon after synthesis. In contrast, transition protein 1 (TP1) was not phosphorylated and did not exhibit multiple electrophoretic forms. © 1994 Wiley-Liss, Inc.
Additional Material:
4 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrd.1080370303
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