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 390 aa precursor that contains a 29 aa signal peptide and a 361 aa proprotein (8). A furin�like convertase processes the proprotein to generate an N�terminal 249 aa latency�associated peptide (LAP) and a C�terminal 112 aa 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 aa279-390 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.