For example, applications to very high molecular weight complexes have benefited significantly from the preparation of highly deuterated molecules where the relaxation times of the remaining NMR probes, typically backbone amide moieties or side-chain methyl groups, are significantly increased. Concomitant with the emergence of these important labeling approaches has been the advancement of new NMR experiments that exploit the labeling in ways that permit the recording of spectra of both increased sensitivity and resolution. Over the past 15 years our laboratory has developed a strategy for studying high molecular weight protein complexes that involves 13CH3 labeling of Ile, Leu and Val methyl positions in an otherwise highly deuterated 12C background. Spectra are recorded that make use of a methyl-TROSY effect that results in significant line-narrowing. Applications of this methodology to a large number of systems have now been AMN107 reported, along with schemes for extending the labeling to Ala and Met methyl positions or for stereospecific incorporation of methyl labels at either proR or proS positions of Leu and Val side-chains. More recently an approach for placement of methyl groups at positions of interest has been introduced involving substitution of the native residue with Cys and subsequently reacting with 13C-methyl-methanethiosulfonate. Ile, Leu, Val comprise approximately 20% of the amino acids in a ‘typical’ protein, and Ala, Met approximately 10% and 2%, respectively. It is thus expected that in many cases these residues, in various combinations, will provide ‘excellent coverage’ of the protein in the sense that they will be found in regions that contribute in important ways to the structure or dynamics of the molecule studied. However, as pointed out by Rule and coworkers these residues are under-represented at protein-nucleic acid interfaces. Moreover, Ile, Leu, Val and Met are predominantly partitioned inside proteins, while Ala has a small preference for the interior as well. Thus, these residues are not effective probes of protein surfaces. The one remaining methyl containing residue, Thr, has both a much higher relative propensity for placement at protein-nucleic acid interfaces and, not surprisingly, also a higher composition on protein surfaces relative to the interior. In addition, of all methyl-containing residues the hydrogen bonding functionality of the Thr side-chain is unique. Finally, like other amino acids, Thr residues can play critically important roles in protein function, such as is the case for the proteasome, a Thr protease, that forms the basis of a large research effort in our laboratory. MiRNAs are endogenous 21–24 nucleotide non-coding RNAs that regulate gene expression in eukaryotes. Mature miRNAs are not directly produced by gene transcription, but are processed from long primary miRNA precursors. Recent reports indicate that miRNAs can not only combine with the 39UTR of target mRNAs but may also bind to sites in the coding region and 59UTR to regulate genes involved in development, virus defense, cell proliferation, apoptosis, and fat metabolism. Studies into miRNA function have mainly focused on a variety of human diseases, particularly cancer, and mainly relate to the use of miRNAs as disease biomarkers and for monitoring drug efficacy. In another important human disease, diabetes, the study by Melkman et al. into the effects of miRNAs on insulin synthesis revealed that knocking out miR-24, miR-26, miR-182, or miR-148 reduced the transcriptional activity of the insulin gene promoter, thereby reducing the level of insulin mRNA.