@article{milam_nicely_feeney_mattos_clark_2007, title={Rapid folding and unfolding of Apaf-1 CARD}, volume={369}, ISSN={["0022-2836"]}, DOI={10.1016/j.jmb.2007.02.105}, abstractNote={Caspase recruitment domains (CARDs) are members of the death domain superfamily and contain six antiparallel helices in an α-helical Greek key topology. We have examined the equilibrium and kinetic folding of the CARD of Apaf-1 (apoptotic protease activating factor 1), which consists of 97 amino acid residues, at pH 6 and pH 8. The results showed that an apparent two state equilibrium mechanism is not adequate to describe the folding of Apaf-1 CARD at either pH, suggesting the presence of intermediates in equilibrium unfolding. Interestingly, the results showed that the secondary structure is less stable than the tertiary structure, based on the transition mid-points for unfolding. Single mixing and sequential mixing stopped-flow studies showed that Apaf-1 CARD folds and unfolds rapidly and suggest a folding mechanism that contains parallel channels with two unfolded conformations folding to the native conformation. Kinetic simulations show that a slow folding phase is described by a third conformation in the unfolded ensemble that interconverts with one or both unfolded species. Overall, the native ensemble is formed rapidly upon refolding. This is in contrast to other CARDs in which folding appears to be dominated by formation of kinetic traps.}, number={1}, journal={JOURNAL OF MOLECULAR BIOLOGY}, author={Milam, Sara L. and Nicely, Nathan I. and Feeney, Brett and Mattos, Carla and Clark, A. Clay}, year={2007}, month={May}, pages={290–304} }
 @article{nicely_kosak_serrano_mattos_2004, title={Crystal structures of Ral-GppNHp and Ral-GDP reveal two binding sites that are also present in Ras and Rap}, volume={12}, ISSN={["1878-4186"]}, DOI={10.1016/j.str.2004.08.011}, abstractNote={RalA is a GTPase with effectors such as Sec5 and Exo84 in the exocyst complex and RalBP1, a GAP for Rho proteins. We report the crystal structures of Ral-GppNHp and Ral-GDP. Disordered switch I and switch II, located away from crystal contacts, are observed in one of the molecules in the asymmetric unit of the Ral-GppNHp structure. In the other molecule in the asymmetric unit, a second Mg(2+) ion is bound to the GppNHp gamma-phosphate in an environment in which switch I is pulled away from the nucleotide and switch II is found in a tight beta turn. Clustering of conserved residues on the surface of Ral-GppNHp identifies two putative sites for protein-protein interaction. One site is adjacent to switch I. The other is modulated by switch II and is obstructed in Ral-GDP. The Ral structures are discussed in the context of the published structures of the Ral/Sec5 complex, Ras, and Rap.}, number={11}, journal={STRUCTURE}, author={Nicely, NI and Kosak, J and Serrano, V and Mattos, C}, year={2004}, month={Nov}, pages={2025–2036} }