Common functions or only phylogenetically related? The large family of PLAC8 motif-containing/PCR genes
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PLAC8 motif-containing proteins form a large family and members can be found in fungi, algae, higher plants and animals. They include the PCR proteins of plants. The name giving PLAC8 domain was originally found in a protein residing in the spongiotrophoblast layer of the placenta of mammals. A further motif found in a large number of these proteins including several PCR proteins is the CCXXXXCPC or CLXXXXCPC motif. Despite their wide distribution our knowledge about the function of these proteins is very limited. For most of them two membrane-spanning α-helices are predicted, indicating that they are membrane associated or membrane intrinsic proteins. In plants PLAC8 motif-containing proteins have been described to be implicated in two very different functions. On one hand, it has been shown that they are involved in the determination of fruit size and cell number. On the other hand, two members of this family, AtPCR1 and AtPCR2 play an important role in transport of heavy metals such as cadmium or zinc. Transport experiments and approaches to model the 3_D structure of these proteins indicate that they could act as transporters for these divalent cations by forming homomultimers. In this minireview we discuss the present knowledge about this protein family and try to give an outlook on how to integrate the different proposed functions into a common picture about the role of PLAC8 motif-containing proteins.
Keywordsfruit size heavy metal mechanosensitive PLAC8 transport
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- Krämer, U., and Clemens, S. (2006). Functions and homeostasis of zinc, copper, and nickel in plants. In Molecular Biology of Metal Homeostasis and Detoxification from Microbes to Man, M.J. Tamás, and E. Martinoia, eds. (Berlin, Germany: Springer), pp. 214–272.Google Scholar
- Marschner, H. (1995). Mineral Nutrition of Higher Plants. (San Diego: Academic Press).Google Scholar
- Nakagawa, Y., Katagiri, T., Shinozaki, K., Qi, Z., Tatsumi, H., Furuichi, T., Kishigami, A., Sokabe, M., Kojima, I., Sato, S., et al. (2007). Arabidopsis plasma membrane protein crucial for Ca2+ influx and touch sensing in roots. Proc. Natl. Acad. Sci. USA 104, 3639–3644.PubMedCrossRefGoogle Scholar
- Song, W.Y., Martinoia, E., Lee, J., Kim, D., Kim, D.Y., Vogt, E., Shim, D., Choi, K.S., Hwang, I., and Lee, Y. (2004). A novel family of cys-rich membrane proteins mediates cadmium resistance in Arabidopsis. Plant Physiol.135, 1027–1039.Google Scholar
- Van der Zaal, B.J., Neuteboom, L.W., Pinas, J.E., Chardonnens, A.N., Schat, H., Verkleij, J.A.C., and Hooykaas, P.J.J. (1999). Overexpression of a novel Arabidopsis gene related to putative zinc-transporter genes from animals can lead to enhanced zinc resistance and accumulation. Plant Physiol. 119, 1047–1056.PubMedCrossRefGoogle Scholar