Structural models of PLD3 and PLD4 (IMAGE) Scripps Research Institute Caption Structural models of PLD3 and PLD4, enzymes that degrade nucleic acids in the cytoplasm. The enzymes' active (or binding) sites are indicated with black arrows. Credit Scripps Research Usage Restrictions With related coverage and credit License Original 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.