Soluble Host Defense Lectins in Innate Immunity to Influenza Virus
Figure 1
Subunit organization and assembly of mammalian lectins with antiviral activity against IAV. (a) Soluble C-type lectins of the collectin superfamily. Collectin subunits are comprised of 3 identical or similar polypeptide chains associated together to form triple helices. Each polypeptide chain bears a C-terminal CRD attached to a short “neck” region, a longer collagenous domain, and a noncollagenous N-terminal domain. CL-43 exists as a trimer whereas other collectins associate together to form multimers with characteristic “cruciform-like” (e.g., SP-D or conglutinin) or “bouquet-like” structures (e.g., MBL, SP-A) or higher-order oligomers (e.g., SP-D). (b) S-type lectins or galectins are a family of -galactosidase-binding lectins containing homologous CRDs. Galectin-1 consists of a single CRD and a short N-terminal sequence and can form noncovalent dimers. (c) Pentraxin subunits are characterized by an 8 amino acid pentraxin signature (H-x-C-x-S/T-W-x-S/T, where x is any amino acid). Subunits assemble into multimers, usually noncovalently associated pentameric or decameric structures.
