| Research Abstract |
Using antibodies of highly branched β-1,6 glucan prepared from the cells of S. pombe and other commercial antibodies, immunoelectron microscopy revealed that the localization and behavior of the cell wall glucans differed as follows:
1) The highly branched β-1,6 glucan was not detected in the Golgi apparatus but instead was located near this apparatus, or along the cell membrane. Linear β-1,6 glucan, however, was detected in the Golgi. From these data linear β-1,6 glucan was speculated to be synthesized in the endoplasmic reticulum-Golgi system and after passage from the Golgi apparatus, the side chains link, forming a comb-like structure, highly branched β-1,6 glucan reaches the cell surface and anchors galactomannan to the framework of the cell wall.
2) During septum formation β-1,3-and α-1,3-glucans were located in the initial region of the nascent septum providing the first morphological evidence of the future septum formation. Highly branched β-1,6 glucan was not present in the first step, but all glucans appeared throughout the septum until the secondary septum was formed. These data suggest that β-1,6 glucan has a different role in the cell wall formation.
3) In the glucan network, β and α-1,3-glucans were detected on the cell membrane but β-1,6 glucan was not. In the "canal" structure of the glucan network no glucan was detected.
4) α-1,3-glucans synthase Mok 1p appeared in the cell membrane at the site of the initial cytokinesis at the end of cell division. The mutant cell of the mok 1p showed the abnormal structure of the secondary wall, suggesting that this gene controls the development of the secondary cell wall.
5) α-1,3-glucans of low molecular meight were recognized in the Golgi apparatus. This phenomenon means that low molecular α-1,3-glucans localize in the Golgi and are synthesized into higher molecules by synthase located on the cell membrane, then form secondary and tertiary structures.
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