LDL Receptor Related Protein 4 (LRP4) Human Recombinant Protein

LRP4: Mediates SOST-dependent inhibition of bone formation. Functions as a specific facilitator of SOST-mediated inhibition of Wnt signaling. Plays a key role in the formation and the maintenance of the neuromuscular junction (NMJ), the synapse between motor neuron and skeletal muscle. Directly binds AGRIN and recruits it to the MUSK signaling complex. Mediates the AGRIN- induced phosphorylation of MUSK, the kinase of the complex. The activation of MUSK in myotubes induces the formation of NMJ by regulating different processes including the transcription of specific genes and the clustering of AChR in the postsynaptic membrane. Alternatively, may be involved in the negative regulation of the canonical Wnt signaling pathway, being able to antagonize the LRP6-mediated activation of this pathway. More generally, has been proposed to function as a cell surface endocytic receptor binding and internalizing extracellular ligands for degradation by lysosomes. Defects in LRP4 are the cause of Cenani-Lenz syndactyly syndrome (CLSS). It is a congenital malformation syndrome defined as complete and complex syndactyly of the hands combined with malformations of the forearm bones and similar manifestations in the lower limbs. Defects in LRP4 are the cause of sclerosteosis type 2 (SOST2). A sclerosing bone dysplasia characterized by a generalized hyperostosis and sclerosis leading to a markedly thickened skull, with mandible, ribs, clavicles and all long bones also being affected. Due to narrowing of the foramina of the cranial nerves, facial nerve palsy, hearing loss and atrophy of the optic nerves can occur. Sclerosteosis is clinically and radiologically very similar to van Buchem disease, mainly differentiated by hand malformations and a large stature in sclerosteosis patients. Belongs to the LDLR family.

Protein type: Membrane protein, integral; Receptor, misc.; Cell surface

Chromosomal Location of Human Ortholog: 11p11.2

Cellular Component: cell surface; cell soma; postsynaptic density; dendrite; integral to membrane; flotillin complex; neuromuscular junction

Molecular Function: protein binding; protein homodimerization activity; apolipoprotein binding; calcium ion binding; receptor tyrosine kinase binding

Biological Process: limb development; extracellular matrix organization and biogenesis; regulation of protein amino acid phosphorylation; Wnt receptor signaling pathway; dendrite morphogenesis; endocytosis; odontogenesis of dentine-containing teeth; hair follicle development; synaptic growth at neuromuscular junction; dorsal/ventral pattern formation; negative regulation of ossification; synapse organization and biogenesis; protein heterotetramerization; negative regulation of axonogenesis; embryonic digit morphogenesis; kidney development; proximal/distal pattern formation

Disease: Myasthenic Syndrome, Congenital, 17; Cenani-lenz Syndactyly Syndrome; Sclerosteosis 2