Protein Model (IMAGE) American University Caption The figure shows a model of the receptor, schematically shown as a green ribbon, in complex with its cognate G protein, shown as grey balls. An amino acid residue that has been found to be mutated in some acromegaly patients (residue 308) is shown in red. Credit Prof. Stefano Costanzi/American University Usage Restrictions Proper crediting License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.