Cayman IGF-1R/CD221 Extracellular Domain (human, recombinant)

Insulin-like growth factor 1 receptor (IGF-1R), also known as CD221, is a member of the type II receptor tyrosine kinase family, previously known as the insulin receptor family.¹ It is synthesized as a preproreceptor with a signal peptide that is cleaved by a furin protease to produce an α- and a β-chain.² The mature protein forms homodimers, which are composed of two extracellular α-chain subunits that comprise the ligand-binding domain, a transmembrane domain, and two intracellular β-chain subunits that contain a tyrosine kinase domain and a C-terminal tail containing several phosphorylation sites located in two interactor domains, which are separated by a regulatory domain.^1,3 It is ubiquitously expressed and, when activated by its ligand IGF-1, IGF-1R undergoes autophosphorylation then phosphorylates and activates intracellular proteins, including insulin receptor substrate (IRS) proteins, activating downstream signaling via the PI3K/Akt, Rac, and RAS/RAF/MEK/ERK pathways.¹ Through these signaling pathways, IGF-1R is involved in inhibition of apoptosis and the regulation of cell migration and proliferation. Overexpression or mutation of CD221 is associated with a variety of cancers, and SNPs in CD221 are positively correlated with an increased risk of cancer.⁴ IGF-1R protein levels are increased in neurons of the temporal cortex in postmortem brain tissue from patients with Alzheimer’s disease, as well as around and within amyloid-β plaques.⁵ Increased levels of IGF-1R have been found in orbital fibroblasts, B cells, and T cells from patients with Graves disease.⁶ Formulations containing anti-IGF-1R antibodies have been used in the treatment of Graves orbitopathy. Caymans IGF-1R/CD221 Extracellular Domain (human, recombinant) protein can be used for binding assays. This protein has calculated molecular weights of 81, 23, and 104 kDa for the α subunit, β subunit, and single chain of the receptor, respectively, and a predicted N-terminus of Glu31 after signal peptide cleavage. By SDS-PAGE, under reducing conditions, the apparent molecular masses are 120, 48, and 150 kDa, respectively, due to glycosylation.

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