1u2h
X-ray Structure of the N-terminally truncated human APEP-1
Structural highlights
DiseaseSPEG_HUMAN Autosomal recessive centronuclear myopathy. The disease is caused by mutations affecting the gene represented in this entry. FunctionSPEG_HUMAN Isoform 3 may have a role in regulating the growth and differentiation of arterial smooth muscle cells. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedBACKGROUND: Human Aortic Preferentially Expressed Protein-1 (APEG-1) is a novel specific smooth muscle differentiation marker thought to play a role in the growth and differentiation of arterial smooth muscle cells (SMCs). RESULTS: Good quality crystals that were suitable for X-ray crystallographic studies were obtained following the truncation of the 14 N-terminal amino acids of APEG-1, a region predicted to be disordered. The truncated protein (termed DeltaAPEG-1) consists of a single immunoglobulin (Ig) like domain which includes an Arg-Gly-Asp (RGD) adhesion recognition motif. The RGD motif is crucial for the interaction of extracellular proteins and plays a role in cell adhesion. The X-ray structure of DeltaAPEG-1 was determined and was refined to sub-atomic resolution (0.96 A). This is the best resolution for an immunoglobulin domain structure so far. The structure adopts a Greek-key beta-sandwich fold and belongs to the I (intermediate) set of the immunoglobulin superfamily. The residues lying between the beta-sheets form a hydrophobic core. The RGD motif folds into a 310 helix that is involved in the formation of a homodimer in the crystal which is mainly stabilized by salt bridges. Analytical ultracentrifugation studies revealed a moderate dissociation constant of 20 microM at physiological ionic strength, suggesting that APEG-1 dimerisation is only transient in the cell. The binding constant is strongly dependent on ionic strength. CONCLUSION: Our data suggests that the RGD motif might play a role not only in the adhesion of extracellular proteins but also in intracellular protein-protein interactions. However, it remains to be established whether the rather weak dimerisation of APEG-1 involving this motif is physiologically relevant. X-ray structure of engineered human Aortic Preferentially Expressed Protein-1 (APEG-1).,Manjasetty BA, Niesen FH, Scheich C, Roske Y, Goetz F, Behlke J, Sievert V, Heinemann U, Bussow K BMC Struct Biol. 2005 Dec 14;5:21. PMID:16354304[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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