Qxxx is an abbreviation, acronym, or slang term which may refer to various things. Here is a comprehensive list of its possible definitions: Qxxxx
Dictyostelium has long been studied for its IQ ([FILV]Qxxx[RK]Gxxxxx[RK]) and IQ-like binding motifs, which serve to mediate calcium-independent CaMBP binding with various myosin light chains. Furthermore, non-IQ binding sites have also been identified within Dictyostelium (Table 3).
At the core of our study lies our objective of exploring whether positively charged amino acids play any part in Sho’s drug sensitizing phenotype. To this end, we generated a mutant Sho protein where all eight arginines of its (RXXX)8 motif have been replaced by glutamines [Sho(Qxxx)8]. Unfortunately, this mutation causes Sho to lose its ability to bind G418 drug to SH-SY5Y cells; nonetheless both WT and mutant Sho localize correctly to cell surfaces; are N-glycosylated (as assessed with treatment with peptide N-glycosidase F) and reach similar expression levels within SH-SY5Y cells.
Sho(Qxxx)8 mutant also shows an equivalent drug-sensitizing phenotype as the WT Sho when tested in an autophagic vacuole formation assay, suggesting the identification of negatively charged amino acid residues can serve as potential drug binding sites and aid the discovery and development of novel anticancer agents. Furthermore, studying CaMBPs within Dictyostelium should offer new insight into mechanisms related to calcium dependent and independent processes like chemotaxis/motility/cell differentiation/osmoregulation etc.