c-Kit, also known as CD117, is a type III receptor tyrosine kinase involved in the proliferation, differentiation, and survival of hematopoietic cells.1,2 It is composed of an N-terminal extracellular domain (ECD) containing five immunoglobulin-like (Ig-like) domains, short transmembrane and juxtamembrane domains, and a C-terminal intracellular region containing the kinase domain. Alternative splicing of KIT produces two isoforms, GNNK+ and GNNK−, that contain or do not contain the tetrapeptide GNNK, respectively, in the juxtamembrane region of the ECD.3 c-Kit is expressed in hematopoietic stem and progenitor cells, as well as certain non-hematopoietic tissues.2 It is activated by the binding of its ligand, stem cell factor (SCF), to the extracellular region, which induces autophosphorylation and the recruitment of signaling molecules to the intracellular region.1 c-Kit signal transduction activates a variety of signaling pathways, including the PI3K/Akt, RAS/MAPK, and JAK/STAT pathways.1,2 The GNNK− isoform of c-Kit undergoes more rapid autophosphorylation and internalization and shows increased MAPK signaling compared with GNNK+ c-Kit, promotes anchorage-independent growth in vitro, and induces tumorigenesis in mice.3 Homozygous knockout of Kit, the gene encoding c-Kit, is embryonic lethal, with mice developing severe anemia in utero.4 KIT is considered a proto-oncogene and activating mutations have been associated with a variety of cancers.1,2 Cayman’s c-Kit/CD117 GNNK− Isoform Extracellular Domain (human, recombinant) protein consists of 502 amino acids, has a calculated molecular weight of 56.7 kDa, and a predicted N-terminus of Gln26 after signal peptide cleavage. By SDS-PAGE, under reducing conditions, the apparent molecular mass of the protein is 86 kDa due to glycosylation.WARNING This product is not for human or veterinary use.
