1. Insertion of the PA Greek key motifs into the membrane occurs when the heptamer is acidified. 2. These histidines all work in conjunction to keep the heptamer from inserting prematurely before endocytosis occurs. 3. The signal sequences are composed of a conserved palindromic heptamer and a conserved AT-rich nonamer. 4. This large binding area explains why previous studies could only bind up to three molecules on a PA63 heptamer . 5. In a recent study the conformation of a water heptamer was determined ( cyclic twisted nonplanar ) using this method 6. This inhibits the receptor from being endocytosed before PA83 is cleaved and before LF or EF can associate with the heptamer . 7. The first base of the heptamer in the signal end is flipped out to avoid the clash in the active center. 8. PA is endocytosed as a soluble heptamer attached to its receptors, with LF or EF attached to the heptamer as cargo. 9. PA is endocytosed as a soluble heptamer attached to its receptors, with LF or EF attached to the heptamer as cargo. 10. Some of this DNA is then deleted, and the RAG complex then induce a nick precisely at the 5'end of the heptamer . 
Mobile