ABSTRACT
The membrane proximal α helix of integrin β subunit cytoplasmic tails plays an important functional role by interacting with various intracellular proteins, namely talin, α-actinin or skelemin. This study was designed to investigate the functional role of 5 highly conserved charged amino acids (R(724), K(725), E(726), E(731), E(733)) within this α helix by site-directed mutagenesis. The result showed that CHO cells expressing the αIIbβ3E726Q mutant had the most prominent phenotype and characterized by defective cell spreading on immobilized fibrinogen. In addition, this E726Q mutation induced membrane blebbing in cells adherent on fibrinogen, and this blebbing could be inhibited by the myosin light chain ATPase inhibitor blebbistatin. It is concluded that the membrane proximal α-helix of integrin β3 subunit is important in linking the phospholipid membrane to the submembraneous actin cortex.
Subject(s)
Animals , Cricetinae , CHO Cells , Cell Surface Extensions , Cricetulus , Heterocyclic Compounds, 4 or More Rings , Chemistry , Integrin beta3 , Genetics , Mutagenesis, Site-Directed , Mutation , Protein Structure, TertiaryABSTRACT
Induced by 42 degrees C, the recombinant engineering bacterial pBV/cpa408 was highly expressed. After having been pelleted by 80% (NH4)2 SO4 and dialysised, the expressed protein was isolated and purified by the gel filtration choromatography. Then according to an amount of 1.0 mg/kg, the Kunming Mice (body weighted 18g) were immuned with the purified protein by intraperitoneal inoculation. One week after the first enhanced immunization, the Kunming Mice were attacked with an amount of 1.0MLD alpha-toxin, in which the eight mice immuned all survive and the control group all died. During the period of immunization, the titre of the mouse's serum antibody was measured by ELISA. One week after the first immunization, the titre of the mice's serum antibody was 1:800, but that of one week after the first enhanced immunization reached to 1:6400.