Grana and stroma lamellae

The mild SDS-PAGE analysis of chlorophyll-protein complexes were performed as in(8). The grana and stroma lamellae were isolated as in(7). The analysis of polypeptide composition of grana and stroma lamellae and re-electrophoresis were performed according to (9). 

CYCLING OF THE PHOTOSYSTEM H REACTION CENTER CORE BETWEEN GRANA AND STROMA LAMELLAE... 

Our results reveal two classes of PSII proteins those that are present only in grana lamellae, and those that display lateral heterogeneity in the thylakoids. The LHCII and the three PSII reaction center proteins, 32 kDa, D2 and cytochrome b559 are present both in grana and stroma lamellae. Such distribution is in agreement with previous reports on the dual location of PSII centers in the two membrane regions (1-3). In contrast, we find that the 51 kDa and 43 kDa PSII proteins are located exclusively in grana lamellae. 

The subthylakoid location of 32 was investigated by fractionating S-methionine pulse-labeled Spirodela into grana and stroma lamellae. Our results indicate that 32 is a product of the grana-located 32 kDa protein. It is exclusively found in the grana partitions and turns over rapidly. 

We used the procedure of Marder et al. (14) to isolate PSII reaction centers from purified grana and stroma lamellae samples. Granal and stroma lamellae reaction centers were... 

In order to investigate to what extent such a lateral migration can occur at lower temperatures, thylakoids phosphorylated at 0°C where subfractionated into grana and stroma lamellae. In contrast to the room temperature control sample the stroma lamellae vesicles showed the same relative amount of LHCII and chi a/b ratio as unphospho-rylated samples (Table II). Moreover, the amount of phospho-LHCII was very low as judged by a low radioactive labelling (Table I). These results clearly show that there is no lateral migration of phospho-LHCII at 0 C and that the kinase activity is restricted to the app-ressed thylakoid regions. 

Barley fHordeum vuloare L. cv. Naomi) seedlings were grown in vermiculite and thylakoids were isolated and fractionated into grana-and stroma-lamellae as described in Ref (13). 

Since grana- and stroma-lamellae demonstrated similar capability to insert pLHCP, it is unlikely that insertion jn vivo is restricted to grana. Two hypothesis are possible either the precursor inserts... 

Cycling of the Photosystem II Reaction Center Core Between Grana and Stroma Lamellae 733 M.L. Ghirardi, F.E. Callahan, S.K. Sopory, T.D, Elich, M. Edelman, A.K. Mattoo... 

Fig. 2.17. Bottom left. Chloroplasts (P) in chlorenchyma of pea leaf. Note the large starch grains within the chloroplast (asterisks). IS, intercellular space V, vacuole. X 780. Right. Electron micrograph of a chloroplast of a leaf of spinach Spinacea oleracea). The chloroplast is surrounded by a double membrane (PM) and the internal membrane system is differentiated into grana (asterisks) and stroma lamellae (open arrows). Osmiophilic droplets (small black arrows) occur in the plastid stroma. The structure of the grana is shown in more detail in the inset top left) as are regions of continuity between the grana and stroma lamellae (large solid arrows). Key CM, cell membrane CW, cell wall SG, starch grain ...

Chloroplasts fill most of the cytoplasm around the junction of three cells of Arabidopsis thaliana seen in this micrograph. Both grana stacks and stroma lamellae (pictured in more detail in Fig. 23-19) can be seen. Also present are several small mitochondria. Portions of the large vacuoles, characteristic of plant cells, are seen at top, right, and bottom. Micrograph courtesy of Kenneth Moore. 

The green photosynthetic organelles of plants resemble mitochondria. Chloroplasts are about 0.2 fJLm in diameter and surrounded by a double-layered lipoprotein membrane about 100 A thick. The two major components of chloroplasts are the membrane system and the stroma. The membrane system contains grana and interconnecting lamellae which carry the chlorophyll molecules, whereas the stroma contains ribosomes (70S) and both RNA and DNA. In spite of the presence of DNA, chloroplasts (like mitochondria) are not autonomous but depend for many of their proteins on nuclear DNA and cytoplasmic ribosomes. Liposoluble spheres containing carotinoids are also present (Mercer, 1960). See Section 4.6 for the many herbicides whose selectivity is exerted on the chloroplasts. 

TABLE I -polypeptides Spirodela Quantitation of the relative distribution of the PSII between grana (G) and stroma lamellae (S) in (Adapted from ref, 10). ... 

FIGURE 1. Thin section of part of an isolated chloroplast showing the internal thylakoid membrane system which consists of appressed grana lamellae (g) and non-appressed stroma lamellae (s) embedded in the stroma protein matrix and surrounded by a double membrane envelope (e). 

The membranes of chloroplast are rather complex. The lamellae may occur singly, and these are called stromal or intergranal lamellae (intergrana) or they may be stacked like coins, when they are termed granal lamellae (grana), and the individual "coins" are called thylakoids. In cross section, the lamellae look like pairs of membranes separating a narrow internal space (the lumen) from the external stroma. 

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