After being synthesized on the ribosome, all proteins must fold into their native three-dimensional structures to be able to perform their defined cellular role. Although all basic information for proper folding is coded within the amino acid sequence, the process of protein folding is far too complex in the super crowded cellular environment. Protein folding is perturbed under stressful conditions, as well by mutations. Specialized proteins and machines called the molecular chaperones with some energy expenditure facilitate productive protein folding and protect proteins from mis-folding and aggregation. Although molecular chaperones have an undeniable role in maintaining protein homeostasis under stress conditions, their involvement in housekeeping functions is well accepted as well. Problems in folding affect protein activity and efficiency, causing various defects and diseases. We are interested in studying how various molecular chaperones affect cellular protein homeostasis in a cell. We use yeasts, plant and fruit-flies as model organisms to understand chaperone function and evolution.