RESUMEN
We demonstrate the preferential orders of molecular chaperones glucose-regulated protein 94 (GRP94), binding immunoglobulin protein (BiP), and calreticulin (CRT) in an endoplasmic reticulum (ER) fraction from rat liver using columns conjugated with denatured myoglobin, RNase A, or ß-lactoglobulin as client proteins in the presence or absence of ATP. The results showed that BiP, CRT, and GRP94 preferentially contributed myoglobin, RNase A, and ß-lactoglobulin, respectively, in the presence of ATP. In the absence of ATP, GRP94 and CRT preferentially recognized misfolded myoglobin (α-helix-rich protein), whereas BiP preferentially recognized misfolded RNase A (α-helix/ß-sheet mixed protein) and ß-lactoglobulin (ß-sheet-rich protein). The preferential order of ER chaperones may be dynamically regulated by ER conditions and the higher-order structure of client proteins.