1r14
From Proteopedia
Carbohydrate recognition and neck domains of surfactant protein A (Sp-A) containing samarium
Overview
Surfactant protein A (SP-A), one of four proteins associated with pulmonary surfactant, binds with high affinity to alveolar phospholipid membranes, positioning the protein at the first line of defense against inhaled pathogens. SP-A exhibits both calcium-dependent carbohydrate binding, a characteristic of the collectin family, and specific interactions with lipid membrane components. The crystal structure of the trimeric carbohydrate recognition domain and neck domain of SP-A was solved to 2.1-A resolution with multiwavelength anomalous dispersion phasing from samarium. Two metal binding sites were identified, one in the highly conserved lectin site and the other 8.5 A away. The interdomain carbohydrate recognition domain-neck angle is significantly less in SP-A than in the homologous collectins, surfactant protein D, and mannose-binding protein. This conformational difference may endow the SP-A trimer with a more extensive hydrophobic surface capable of binding lipophilic membrane components. The appearance of this surface suggests a putative binding region for membrane-derived SP-A ligands such as phosphatidylcholine and lipid A, the endotoxic lipid component of bacterial lipopolysaccharide that mediates the potentially lethal effects of Gram-negative bacterial infection.
About this Structure
1R14 is a Single protein structure of sequence from Rattus norvegicus. Full crystallographic information is available from OCA.
Reference
Crystal structure of trimeric carbohydrate recognition and neck domains of surfactant protein A., Head JF, Mealy TR, McCormack FX, Seaton BA, J Biol Chem. 2003 Oct 31;278(44):43254-60. Epub 2003 Aug 11. PMID:12913002 Page seeded by OCA on Sat May 3 06:56:56 2008
