KIR2DS4 is a product of gene conversion with KIR3DL2 that introduced specificity for HLA-A*11 while diminishing avidity for HLA-C

Human killer cell immunoglobulin-like receptors (KIRs) are distinguished by expansion of activating KIR2DS, whose ligands and functions remain poorly understood. The oldest, most prevalent KIR2DS is KIR2DS4, which is represented by a variable balance between “full-length” and “deleted” forms. We find that full-length 2DS4 is a human histocompatibility leukocyte antigen (HLA) class I receptor that binds specifically to subsets of C1+ and C2+ HLA-C and to HLA-A*11, whereas deleted 2DS4 is nonfunctional. Activation of 2DS4+ NKL cells was achieved with A*1102 as ligand, which differs from A*1101 by unique substitution of lysine 19 for glutamate, but not with A*1101 or HLA-C. Distinguishing KIR2DS4 from other KIR2DS is the proline–valine motif at positions 71–72, which is shared with KIR3DL2 and was introduced by gene conversion before separation of the human and chimpanzee lineages. Site-directed swap mutagenesis shows that these two residues are largely responsible for the unique HLA class I specificity of KIR2DS4. Determination of the crystallographic structure of KIR2DS4 shows two major differences from KIR2DL: displacement of contact loop L2 and altered bonding potential because of the substitutions at positions 71 and 72. Correlation between the worldwide distributions of functional KIR2DS4 and HLA-A*11 points to the physiological importance of their mutual interaction

Morpholinium Trifluoroacetate-Catalyzed Aldol Condensation of Acetone with both Aromatic and Aliphatic Aldehydes

We report a highly efficient, general and practical method for the aldol condensation of acetone with aromatic and aliphatic aldehydes, using morpholinium trifluoroacetate as a catalyst

Pd-catalyzed synthesis of functionalized arylketones from boronic acids and carboxylic acids activated in situ with dimethyl dicarbonate

Highly efficient catalyst systems were developed that allow the palladium-catalyzed cross-coupling of arylboronic acids with carboxylic acids activated in situ with dimethyl dicarbonate at room temperature. As byproducts, only methanol, CO2, and boric acid are formed, making the isolation of the products particularly easy. Thus, many functionalized ketones are conveniently accessible from boronic and carboxylic acids in the presence of 1.5 equivalents of dimethyl dicarbonate and Pd(OAc)(2)-P(p-MeOPh)(3) as the catalyst, The presence of small amounts of water and a ligand-Pd ratio lower than 4 is crucial for achieving good yields at low temperatures