Immunogold localization of photosystem I and photosystem II light-harvesting complexes in cryptomonad thylakoids

Document Type

Article

Publication Date

1-1-1992

Publication Title

Biology of the Cell

Volume

74

Issue

C

First Page

187

Keywords

Cryptomonas rufescens, light-harvesting protein, photosystems, phycoerythrin, thylakoids

Last Page

194

Abstract

The molecular organization of the thylakoids of Cryptomonas rufescens was studied by immunoelectron microscopy employing antibodies against photosystem (PS)-I and two PS-II antenna proteins. The PS-I complex and the 19-kDa chlorophyll a/c light-harvesting (LH) protein are both localized along the length of the thylakoid membranes. The external membranes of the paired thylakoids are enriched in PS-I whereas the chlorophyll a/c LH protein is more concentrated in the internal or appressed membranes. However, unlike the situation in higher plants and Chlamydomonas, there is not a marked asymmetry in the concentration of PS-I and chorophyll a/c LH protein in the two types of membranes. Double labelling studies of sections and isolated PE-PS-II particles with anti-phycoerythrin and anti-LH confirmed that phycoerythrin is localized in the thylakoid lumen and that this pigment exists in two forms, a fraction closely associated with the thylakoid membranes and another fraction free in the lumen. These results confirm the uniqueness of cryptomonad thylakoids. © 1992.

DOI

10.1016/0248-4900(92)90024-U

ISSN

02484900

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