Graphics (IMAGE) Karolinska Institutet Caption Methylation is a small protein modification that uses SAM as a co-factor. This study shows how SAM is required for mitochondrial function in various organisms. Credit Karolinska Institutet. Usage Restrictions None 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.