Molecular Biology Of The Cell 6th Edition by Bruce Alberts, Alexander Johnson, Julian Lewis, David Morgan, Martin Raff, Keith Roberts, Peter Walter

تمرين 12

0 The affinity of integrins for matrix components can be modulated by changes to their cytoplasmic domains: a process known as inside-out signaling. You have iden- tified a key region in the cytoplasmic domains of integrin that seems to be required for inside-out signaling (Figure Q19-3). Substitution of alanine for either D723 in the chain or R995 in the chain leads to a high level of spontaneous activation, under conditions where the wild-type chains are inactive. Your advisor suggests that you convert the aspartate in the chain to an arginine (D723R) and the arginine in the chain to an aspartate (R995D). You compare all three chains (R995, R995A, and R995D) against all three chains (D723, D723A, and D723R). You find that all pairs have a high level of sponta- neous activation, except D723 vs R995 (the wild type) and D723R vs R995D, which have low levels. Based on these results, how do you think the integrin is held in its inactive state?