4oum | pdb_00004oum
Crystal structure of human Caprin-2 C1q domain
Structural highlights
FunctionCAPR2_HUMAN May regulate the transport and translation of mRNAs, modulating for instance the expression of proteins involved in synaptic plasticity in neurons. Involved in regulation of growth as erythroblasts shift from a highly proliferative state towards their terminal phase of differentiation. May be involved in apoptosis.[1] Publication Abstract from PubMedPreviously, we have identified Caprin-2 as a new regulator in canonical Wnt signaling through a mechanism of facilitating LRP5/6 phosphorylation; moreover, we found that its C-terminal C1q-related domain (Cap2_CRD) is required for this process. Here, we determined the crystal structures of Cap2_CRD from human and zebrafish, which both associate as a homotrimer with calcium located at the symmetric center. Surprisingly, the calcium binding-deficient mutant exists as a more stable trimer than its wild-type counterpart. Further studies showed that this Caprin-2 mutant disabled in binding calcium maintains the activity of promoting LRP5/6 phosphorylation, whereas the mutations disrupting Cap2_CRD homotrimer did impair such activity. Together, our findings suggested that the C-terminal CRD domain of Caprin-2 forms a flexible homotrimer mediated by calcium and that such trimeric assembly is required for Caprin-2 to regulate canonical Wnt signaling. Structural insights into the C1q domain of Caprin-2 in canonical Wnt signaling.,Miao H, Jia Y, Xie S, Wang X, Zhao J, Chu Y, Zhou Z, Shi Z, Song X, Li L J Biol Chem. 2014 Dec 5;289(49):34104-13. doi: 10.1074/jbc.M114.591636. Epub 2014, Oct 20. PMID:25331957[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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