Immunocytochemical Localization of Phosphoribulokinase in Microalgae

Document Type

Article

Publication Date

1-1-1991

Publication Title

Botanica Acta

Volume

104

Issue

5

First Page

367

Keywords

Algae, chloroplast, immunocytochemistry, phosphoribulokinase, pyrenoid, Rubisco

Last Page

373

Abstract

Employing immunogold electron microscopy, the subcellular location of the Calvin cycle enzyme phosphoribulokinase (PRK) was determined for two diverse species of microalgae. In both the red alga Porphyridium cruentum and the green alga Chlamydomonas reinhardtii, PRK was distributed throughout the thylakoid‐containing chloroplast stroma. In contrast, the next enzyme in the pathway, ribulose 1,5‐bisphosphate carboxylase/oxygenase, was predominantly pyrenoid‐localized in both species. In Porphyridium, the chloroplast stroma abuts the pyrenoid but in Chlamydomonas and other green algae, the pyrenoid appears encased in a starch sheath. Unique inclusions found in the pyrenoid of Chlamydomonas were immunolabelled by anti‐PRK and thus identified as regions of chloroplast stroma. It is postulated that such PRK‐containing stromal inclusions in the pyrenoids of Chlamydomonas and perhaps other green algae provide a means for exchange of Calvin cycle metabolites between pyrenoid and stroma. 1991 Deutsche Botanische Gesellschaft/German Botanical Society

DOI

10.1111/j.1438-8677.1991.tb00243.x

ISSN

09328629

E-ISSN

14388677

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