Alpha actinin 3

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Alpha actinin 3
Alpha actinin 3
according to PDB  1TJT

Existing structure data : 1TJT , 1WKU , 3LUE

Properties of human protein
Mass / length primary structure 901 amino acids
Secondary to quaternary structure Homodimer; Heterodimer with ACTN2
Identifier
Gene name ACTN3
External IDs
Occurrence
Homology family alpha actinin
Parent taxon Vertebrates

Alpha-actinin 3 (ACTN3) is a protein in vertebrates that combines the structural protein actin with other structural proteins and thus participates in muscle contraction . Its expression is limited to the skeletal muscles . It is located in the structure called the Z-disk and the dense bodies, where it helps anchor the myofibrillary actin filaments .

In humans, was mutation (rs1815739; R577X) in ACTN3 - gene identified that results in a significant percentage of the population to a shortened version of the alpha-actinin third Worldwide, this variant exists in around 20% of the population. In general, African Americans have the lowest incidence of this mutation while Asians have the highest. Scientists believe that fluctuations in this gene evolved to adapt to energy consumption requirements in different parts of the world.

Studies show that the fiber types are linked to ACTN3, so individuals with a high percentage of fast muscle fibers have the non-mutated version of the gene. Studies by elite athletes have also shown that the ACTN3 gene can influence athletic performance . While the non-mutated version of the gene is associated with a sprint performance, the mutated version is associated with athletic endurance performance.

Function of ACTN3 in muscle fibers

Actin filaments are stabilized by actin-binding proteins called actinins. There are two main types: Type 2 and Type 3. Each of them is encoded by a specific gene , ACTN2 and ACTN3 . ACTN2 is expressed in all skeletal muscle fibers, but ACTN3 is only expressed in fast (FT) fibers.

Fast (FT = fast twitch) versus slow (ST = slow twitch) muscle fibers

Skeletal muscles are made up of long cylindrical cells called muscle fibers . Each muscle fiber is made up of long tubes called myofibrils, which in turn consist of filaments. There are two types of filaments: actin (thin filaments) and myosin (thick filaments), which are arranged in parallel. When the muscles contract, both filaments shift against each other.

There are two types of muscle fibers, slow twitch and fast twitch fibers. The slow fibers work in the aerobic range and can maintain low force for an extended period of time. In contrast, fast fibers are stronger and work in the anaerobic area. They are mainly used for a short period of time when a lot of effort is required.

Muscle composition in elite athletes

Each individual has an average equal distribution of fast and slow muscle fibers, but Olympic sprinters tend to have about 80% fast fiber. In contrast, Olympic marathon participants have about 80% slow fibers. There is a difference of opinion as to whether exercise can change the percentage of fiber types over time. For this reason, it is currently believed that heredity or genetics play the greatest role in the formation of the various types of fiber.

See also

literature

  1. ↑ North KN, Yang N, Wattanasirichaigoon D, Mills M, Easteal S, Beggs AH: A common nonsense mutation results in alpha-actinin-3 deficiency in the general population . In: Nat. Genet. . 21, No. 4, April 1999, pp. 353-4. doi : 10.1038 / 7675 . PMID 10192379 .
  2. ↑ Yang N, MacArthur DG, Gulbin JP, Hahn AG, Beggs AH, Easteal S, North K: ACTN3 genotype is associated with human elite athletic performance . In: Am. J. Hum. Genet. . 73, No. 3, September 2003, pp. 627-31. doi : 10.1086 / 377590 . PMID 12879365 . PMC 1180686 (free full text).
  3. ↑ Niemi AK, Majamaa K: Mitochondrial DNA and ACTN3 genotypes in Finnish elite endurance and sprint athletes . In: Eur. J. Hum. Genet. . 13, No. 8, August 2005, pp. 965-9. doi : 10.1038 / sj.ejhg.5201438 . PMID 15886711 .
  4. ↑ Moran CN, Yang N, Bailey ME, Tsiokanos A, Jamurtas A, MacArthur DG, North K, Pitsiladis YP, Wilson RH: Association analysis of the ACTN3 R577X polymorphism and complex quantitative body composition and performance phenotypes in adolescent Greeks . In: Eur. J. Hum. Genet. . 15, No. 1, January 2007, pp. 88-93. doi : 10.1038 / sj.ejhg.5201724 . PMID 17033684 .
  5. ↑ Roth SM, Walsh S, Liu D, Metter EJ, Ferrucci L, Hurley BF: The ACTN3 R577X nonsense allele is under-represented in elite-level strength athletes . In: Eur. J. Hum. Genet. . 16, No. 3, March 2008, pp. 391-4. doi : 10.1038 / sj.ejhg.5201964 . PMID 18043716 .

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