BK Channel Building Block (IMAGE) Washington University in St. Louis Caption BK channels are composed of four identical proteins, each of which consists of tight helical coils of protein connected by straight "linkers," so that the unfolded protein looks like a string of beads. Credit Jianmin Cui 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.