The gp38 adhesins of the T4 superfamily: a complex modular determinant of the phage's host specificity.

The tail fiber adhesins are the primary determinants of host range in the T4-type bacteriophages. Among the indispensable virion components, the sequences of the long tail fiber genes and their associated adhesins are among the most variable. The predominant form of the adhesin in the T4-type phages is not even the version of the gene encoded by T4, the archetype of the superfamily, but rather a small unrelated protein (gp38) encoded by closely related phages such as T2 and T6.