CAP-Gly domain: Difference between revisions

The cytoskeletal network contains Cytoskeleton-Associated Proteins (CAPs), including CLIP-170 and dynactins, that function in the organization of microtubules and in the transportation of vesicles and organelles.  CAPs that bind to the +end of microtubules generally contain one or more glycine-rich domains with a well-conserved GKNDG sequence motif<ref>PMID:8480366</ref>, presumably involved in protein-protein binding.  

The first crystal structure of a CAP-Gly domain (PDP file [[1lpl]]), from Caenorhabditis elegans protein F53F4.3, revealed a novel protein fold containing a small 5-strand antiparallel beta-barrel and an N-terminal helix.  The GKNDG sequence is in two consecutive turns of a surface loop, at one side of a groove (as shown in image at left). The groove is lined by a large, concave patch of residues highly conserved among the related sequences<ref>PMID:12221106</ref>.  In the crystal, a dimer is formed by binding of the C-terminus of each chain into the GKNDG groove of the other chain.   

[[1tov|1TOV]] is a rebuilt and re-refined version of the same dataset from [[1lpl| 1LPL]], giving an improvement of about 4% in Rfree, identifying a sulfate (seen in both 2D and interactive images), and adding 3 more residues of ordered helix toward the N-terminal end of the domain fragment.  Both are from the SouthEast Collaboratory for Structural Genomics (SECSG), solved by single wavelength sulfur-anomalous phasing.  The new [[1tov]] structure was produced as part of a systematic 30-structure test of the then-new MolProbity methods for diagnosing and correcting problems in crystallographic models<ref>PMID:15965733</ref>.