Plant Science

Mapping Out Diversity

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Science  12 Dec 2008:
Vol. 322, Issue 5908, pp. 1610
DOI: 10.1126/science.322.5908.1610b

In plants, microtubules in the cell cortex help align cellulose fibrils in the cell wall, which in turn shape tissue structure. Microtubules are constantly in flux: growing at one end, disintegrating at the other end, and bundling together with neighbors. Microtubule-associated proteins (MAPs), specifically the MAP65 family, add some control to this otherwise fluid and self-assembling skeleton. Although animals have 1 or 2 MAP65 homologs, Arabidopsis has 9, and rice has 11. Smertenko et al. have analyzed this abundance and find that the genes fall into five families. Both rice and Arabidopsis, representing the ancient evolutionary divergence between monocots and dicots, have representatives of each of the five families. The MAP65 isoforms show different localizations within the cell and variable expression during development or through the cell cycle. Some are ubiquitously expressed, and others are unique to a particular tissue type, such as pollen. Some are preferentially expressed during G1 and others during G2. The domain responsible for this diversity among the MAP65 proteins seems to harbor the similarly diverse phosphorylation sites. — PJH

Plant Cell 20, 10.1105/tpc.108.063362 (2008).

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