myosin (thick laments)--that slide over each other to cause muscles to contract, a literal shortening of the muscle. Actin laments, which are necessary to this process, are stabilized by actin-binding proteins. One actin-binding protein called alpha-actinin 3 (ACTN3) is expressed only in fast-twitch muscle ber, the crown jewel of shot-putters and bodybuilders worldwide. It turns out that both of my chromosomes (one from Mammy and one from Pappy Ferriss) contain the R577X variant of the ACTN3 gene, a mutation that results in a complete de ciency of our most desired ACTN3. This variant, amusingly called a "nonsense allele," is found in more than a billion humans worldwide. Sad Christmas. The cover letter from Gist Sports began with the following headline, which, in good humor, lacks an exclamation point: Congratulations Tim Ferriss. Your Genetic Advantage: Endurance Sports.
annaabi.ee 
