IGFBP3 Protein (NBP1-46069) (25 ug)

IGFBP-3 is a member of the insulin-like growth factor binding protein (IGFBP) family. This family includes IGFBP-1 to IGFBP-6 that bind to the insulin-like growth factors (IGFs), thus regulating the half-life, activity, transport, and tissue distribution of the IGFs. Structurally, the IGFBP family of proteins is defined by highly homologous amino and carboxy terminal domains with a structurally diverse central region. The IGF binding motifs exist in the amino and carboxy terminal regions. The carboxy terminal domains may also be involved in interactions with numerous other molecules that may modulate IGF-binding as well as conferring IGF-independent function. IGFBP-3 is the most abundant IGFBP found in human serum where it is predominantly found as a ternary complex with IGF-I or IGF-II and the acidlabile subunit (ALS). This complex accounts for the majority of circulating IGF. Functionally, IGFBP-3 has been observed to exhibit both cell growth promoting and inhibiting effects depending on its effect on the bioavailability of IGF, and its IGF-independent function. IGFBP-3 is a 264 amino acid glycoprotein. In addition to glycosylation IGFBP-3 can also be phosphorylated and these post-translational modifications influence functional activity of IGFBP-3 by modulating tissue targeting, cell interaction and susceptibility to proteolytic cleavage. IGFBP-3 contains three potential N-linked glycosylation sites (Asn-X-Ser/Thr) located in the central linker domain at Asn 89 Asn 109, and Asn 172, while phosphorylation occurs at Ser 111 and 113. This is a HCX protein. HCX Expression System Details HCX proteins mimic the proteins in the human body because they are expressed from human, rather than animal, insect or bacterial cells. This process gives them human post-translational modifications. Recombinant DNA techniques allow a human protein with the correct amino acid sequence to be expressed in a non-human cell line. However, non-human cells lack the appropriate cellular machinery, such as specific glycosyltransferases, necessary to produce the correct human post-translational modifications of a protein. An extreme example is seen in E. coli cells, which produce recombinant proteins with no glycosylation, as the above figure illustrates. Rodent and yeast cells are able to glycosylate proteins, but they are still different from glycosylation in human cells. Expression System Resultant Proteins Human (e.g. K562, HEK293) Correct amino acid sequence Human post-translational modifications Rodent (e.g. CHO, NSO) Correct amino acid sequence Some natural glycosylation - not human-like Yeast (e.g. Pichia) Correct amino acid sequence Some natural glycosylation - not human-like E.Coli Correct amino acid sequence No PTMs Although there have been significant attempts to make non-human cell derived cytokines more human-like, there is a growing awareness that in many instances, particularly in therapeutics, cytokines should mimic those found in the body as closely as possible.