RACK1 protein, molecular model. RACK1 stands for Receptor for Activated C Kinase 1. This protein is also known as guanine nucleotide-binding protein subunit beta-2-like 1 (GNB2L1). It is a scaffolding protein that regulates numerous signalling cascades, helping to restrain, locallise, co-ordinate and insulate the effects of other proteins. RACK1 folds into a beta-propeller shape. The structure shown here consists of three protein chains (red, blue, green).