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Polypyrimidine tract binding (PTB) proteins

Project leader: Il Ho Kang (ihkang@iastate.edu)

Polypyrimidine tract binding proteins bind to RNA to mediate splicing, translation, stability, and localization of the partner RNA. They generally contain four RNA recognition motifs (RRM) and bind to clusters of CU elements of 3-5 nt each. In potato, three groups of PTBs have been identified; one group contains four RRMS, another only two RRMs and a third that contains only one RRM.

A PTB protein of pumpkin, designated RBP50, is the core RNA-binding protein of a mobile RNA/protein complex (Ham et al., 2009). Gel mobility-shift assays have demonstrated the role of specific polypyrimidine tract binding motifs in the phloem RNAs of pumpkin, CmGAIP and CmPP16-1, that mediate binding to this PTB protein. In this system, phloem RNAs and the CmRBP50 protein provide the basis for a mobile ribonucleoprotein complex containing as many as sixteen proteins. We predict that PTB proteins of potato play a similar role. For more information on PTB proteins, see Auweter and Allain (2008).

from Sawicka et al (2008)