Abstract
When mating-type minus (mt−) and plus (mt+) cells of theClosterium peracerosum-strigosum-littorale complex were mixed together in a nitrogen-deficient mating medium, cells of both types released protoplasts, this release being the first step in the process of conjugation. Release of protoplasts by mt− cells also proceeded without pairing in a medium in which mt− and mt+ cells had previously been cultured together. A protein with the ability to induce the release of protoplasts was purified from this medium by sequential column-chromatographic steps, and named PR-IP (protoplast-release-inducing protein). The PR-IP had an apparent molecular mass (Mr) of 95000 on gel filtration and could be separated into several isoforms by anion-exchange chromatography. Each isoform consisted of two glycopolypeptides of Mrs 42000 and 19000, while the deglycosylated polypeptides had Mrs of 34000 and 18000, respectively. From an analysis of dose-response curves, the numbers of PR-IP molecules required for the release of a protoplast by a single cell was calculated as 1.5·109 and the concentration required for 50% of the maximum response (ED50) as 4.1·10−9M. We suggest that the PR-IP is a biologically active glycoprotein which induces the release of gametic protoplasts from mt− cells of thisClosterium complex.
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Abbreviations
- kDa:
-
kilodalton
- MI medium:
-
nitrogen-deficient mating medium
- Mr :
-
apparent molecular mass
- PI:
-
protoplastrelease-inducing
- PR-IP:
-
protoplast-release-inducing protein
- SDS-PAGE:
-
sodium dodecyl sulfate-polyacrylamide gel electrophoresis
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Sekimoto, H., Satoh, S. & Fujii, T. Biochemical and physiological properties of a protein inducing protoplast release during conjugation in theClosterium peracerosum-strigosum-littorale complex. Planta 182, 348–354 (1990). https://doi.org/10.1007/BF02411384
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DOI: https://doi.org/10.1007/BF02411384