Tubulin Assembly Machine (IMAGE) University of California - Davis Caption UC Davis researchers show how four proteins come together to make the machine that assembles tubulin, the building block of microtubules. Credit Jawdat Al-Bassam, UC Davis Usage Restrictions May be used with acknowledgement of the source. 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.