SUMO Enzyme (image) Max-Planck-Gesellschaft Caption A protein structure (synaptonemal complex) forms between the homologous chromosomes in the presence of the step-2 enzyme modified with SUMO. If the step-2 enzyme cannot be modified with SUMO, the complex is completely absent. Credit Martin Xaver, modified by Andrea Pichler Usage Restrictions None 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.