RESUMEN
Loss or duplication of chromosome segments can lead to further genomic changes associated with cancer. However, it is not known whether only a select subset of genes is responsible for driving further changes. To determine whether perturbation of any given gene in a genome suffices to drive subsequent genetic changes, we analyzed the yeast knockout collection for secondary mutations of functional consequence. Unlike wild-type, most gene knockout strains were found to have one additional mutant gene affecting nutrient responses and/or heat-stress-induced cell death. Moreover, independent knockouts of the same gene often evolved mutations in the same secondary gene. Genome sequencing identified acquired mutations in several human tumor suppressor homologs. Thus, mutation of any single gene may cause a genomic imbalance, with consequences sufficient to drive adaptive genetic changes. This complicates genetic analyses but is a logical consequence of losing a functional unit originally acquired under pressure during evolution.
Asunto(s)
Genoma Fúngico , Saccharomyces cerevisiae/genética , Adaptación Biológica/genética , Secuencia de Bases , Evolución Molecular , Eliminación de Gen , Técnicas de Inactivación de Genes , Heterogeneidad Genética , Inestabilidad Genómica , Humanos , Mutación , Neoplasias/genética , Fenotipo , Análisis de Secuencia de ADN , Estrés Fisiológico/genéticaRESUMEN
Golgin-160 is a member of the golgin family of proteins, which have been implicated in the maintenance of Golgi structure and in vesicle tethering. Golgin-160 is atypical; it promotes post-Golgi trafficking of specific cargo proteins, including the ß-1 adrenergic receptor (ß1AR), a G protein-coupled receptor. Here we show that golgin-160 binds directly to the third intracellular loop of ß1AR and that this binding depends on three basic residues in this loop. Mutation of the basic residues does not affect trafficking of ß1AR from the endoplasmic reticulum through the Golgi complex, but results in reduced steady-state levels at the plasma membrane. We hypothesize that golgin-160 promotes incorporation of ß1AR into specific transport carriers at the trans-Golgi network to ensure efficient delivery to the cell surface. These results add to our understanding of the biogenesis of ß1AR, and suggest a novel point of regulation for its delivery to the plasma membrane.
Asunto(s)
Autoantígenos/metabolismo , Proteínas de la Membrana/metabolismo , Receptores Adrenérgicos beta 1/metabolismo , Secuencia de Aminoácidos , Autoantígenos/química , Autoantígenos/genética , Membrana Celular/metabolismo , Retículo Endoplásmico/metabolismo , Aparato de Golgi/metabolismo , Proteínas de la Matriz de Golgi , Células HeLa , Humanos , Proteínas de la Membrana/química , Proteínas de la Membrana/genética , Mutación , Unión Proteica , Estructura Terciaria de Proteína , Transporte de Proteínas , Receptores Adrenérgicos beta 1/químicaRESUMEN
Cold temperature blocks used to synchronize protein trafficking inhibit GBF1 function, leading to a decrease in ARF1-GTP levels and mislocalization of the ARF1 effector golgin-160. Several other, but not all, Golgi proteins including ARL1 also mislocalize. ARF1 activity and golgin-160 localization require more than 30 min to recover from these blocks.