3n1o | pdb_00003n1o
Crystal structure of IhhN
Structural highlights
Disease[IHH_HUMAN] Brachydactyly type A1;Acrocapitofemoral dysplasia. Defects in IHH are the cause of brachydactyly type A1 (BDA1) [MIM:112500]. BDA1 is an autosomal dominant disorder characterized by middle phalanges of all the digits rudimentary or fused with the terminal phalanges. The proximal phalanges of the thumbs and big toes are short.[1] [2] Defects in IHH are a cause of acrocapitofemoral dysplasia (ACFD) [MIM:607778]. ACFD is a disorder characterized by short stature of variable severity with postnatal onset. The most constant radiographic abnormalities are observed in the tubular bones of the hands and in the proximal part of the femur. Cone-shaped epiphyses or a similar epiphyseal configuration with premature epimetaphyseal fusion result in shortening of the skeletal components involved. Cone-shaped epiphyses were also present to a variable extent at the shoulders, knees, and ankles.[3] Function[IHH_HUMAN] Intercellular signal essential for a variety of patterning events during development. Binds to the patched (PTC) receptor, which functions in association with smoothened (SMO), to activate the transcription of target genes. Implicated in endochondral ossification: may regulate the balance between growth and ossification of the developing bones. Induces the expression of parathyroid hormone-related protein (PTHRP) (By similarity). 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 PubMedHedgehog (Hh) signaling proteins stimulate cell proliferation, differentiation, and tissue patterning at multiple points in animal development. A single Hh homolog is present in Drosophila, but three Hh homologs, Sonic Hh, Indian Hh, and Desert Hh, are present in mammals. Distribution, movement, and reception of Hh signals are tightly regulated, and abnormal Hh signaling is associated with developmental defects and cancer. In addition to the integral membrane proteins Patched and Smoothened, members of the Drosophila Ihog family of adhesion-like molecules have recently been shown to bind Hh proteins with micromolar affinity and positively regulate Hh signaling. Cell adhesion molecule-related, down-regulated by oncogenes (CDO) and Brother of CDO (BOC) are the closest mammalian relatives of Drosophila Ihog, and CDO binds Sonic Hh with micromolar affinity and positively regulates Hh signaling. Despite these similarities, structural and biochemical studies have shown that Ihog and CDO utilize nonorthologous domains and completely different binding modes to interact with cognate Hh proteins. We report here biochemical and x-ray structural studies of Sonic, Indian, and Desert Hh proteins both alone and complexed with active domains of CDO and BOC. These results show that all mammalian Hh proteins bind CDO and BOC in the same manner. We also show that interactions between Hh proteins and CDO are weakened at low pH. Formation of Hh-mediated Hh oligomers is thought to be an important feature of normal Hh signaling, but no conserved self-interaction between Hh proteins is apparent from inspection of 14 independent Hh-containing crystal lattices. All mammalian Hedgehog proteins interact with cell adhesion molecule, down-regulated by oncogenes (CDO) and brother of CDO (BOC) in a conserved manner.,Kavran JM, Ward MD, Oladosu OO, Mulepati S, Leahy DJ J Biol Chem. 2010 Aug 6;285(32):24584-90. Epub 2010 Jun 1. PMID:20519495[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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