TGF-b1, Recombinant, Human (Transforming Growth Factor Beta 1, TGFB1)

TGF-b1 (transforming growth factor beta 1) is one of three closely related mammalian members of the large TGF-b superfamily that share a characteristic cystine knot structure (1-7). TGF-b1, -2 and -3 are highly pleiotropic cytokines that are proposed to act as cellular switches that regulate processes such as immune function, proliferation and epithelial-mesenchymal transition (1-4). Each TGF-b isoform has some non-redundant functions; for TGF-b1, mice with targeted deletion show defects in hematopoiesis and endothelial differentiation, and die of overwhelming inflammation (2). Human TGF-b1 cDNA encodes a 390aa precursor that contains a 29aa signal peptide and a 361aa proprotein (8). A furin-like convertase processes the proprotein to generate an N-terminal 249aa latency-associated peptide (LAP) and a C-terminal 112aa mature TGF-b1 (8, 9). Disulfide-linked homodimers of LAP and TGF-b1 remain non-covalently associated after secretion, forming the small latent TGF-b1 complex (8-10). Covalent linkage of LAP to one of three latent TGF-b binding proteins (LTBPs) creates a large latent complex that may interact with the extracellular matrix (9, 10). TGF-b is activated from latency by pathways that include actions of the protease plasmin, matrix metalloproteases, thrombospondin 1 and a subset of integrins (10). Mature human TGF-b1 shares 100%aa identity with pig, dog and cow TGF-b1, and 99%aa identity with mouse, rat and horse TGF-b1. It demonstrates cross-species activity (1). TGF-b1 signaling begins with high-affinity binding to a type II ser/thr kinase receptor termed TGF-b RII. This receptor then phosphorylates and activates a second ser/thr kinase receptor, TGF-b RI (also called activin receptor-like kinase (ALK) -5), or alternatively, ALK-1. This complex phosphorylates and activates Smad proteins that regulate transcription (3, 11, 12). Contributions of the accessory receptors betaglycan (also known as TGF-b RIII) and endoglin, or use of Smad-independent signaling pathways, allow for disparate actions observed in response to TGF-b in different contexts (11). Source: Recombinant corresponding to aa270-390 from human TGF-b1 expressed in HEK293 cells (P01137). Molecular Weight: ~12.8kD Biological Activity: Measured by its ability to inhibit the IL-4-dependent proliferation of HT-2 mouse T cells. Endotoxin: <0.10 EU per 1ug of protein by the LAL method Storage and Stability: Lyophilized powder may be stored at -20 degrees C. Stable for 12 months at -20 degrees C. Reconstitute with sterile buffer or ddH2O. Aliquot to avoid repeated freezing and thawing. Store at -20 degrees C. Reconstituted product is stable for 6 months at -20 degrees C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.