Cry1A.105 is a full-length, insecticidal protein consisting of 1177 amino acids with a molecular weight (MW) of 133 kDa. It is a chimeric protein that consists of domains I and II from Cry1Ab or Cry1Ac1, domain III from Cry1F, and the C-terminal domain
from Cry1Ac.

Cry1A.105 was designed using domain exchange strategy to achieve high levels of activity against target lepidopteran insect pests. The domains I and II of Cry1A.105 are 100% identical to the respective domains of Cry1Ab or Cry1Ac. The domain III of Cry1A.105 is 99% identical to the domain III of Cry1F. The C-terminal region of Cry1A.105 is 100% identical to that of Cry1Ac.

Cry1Ac, Cry1Ab and Cry1F are all well known and well characterized insecticidal proteins derived from the soil bacterium Bacillus thuringiensis (Bt).The overall amino acid sequence identity of Cry1A.105 to Cry1Ac, Cry1Ab, and Cry1F is 93.6%, 90.0%, and 76.7%, respectively