TGFβ is a labile (half-life in vivo
of 2-3 minutes) but highly potent cytokine. It plays a crucial role in immune regulation, and is highly fibriogenic.
The TGFβ1 gene encodes a proprotein that contains sequences for the latency-associated peptide (LAP) and the TGFβ peptide chains. Amino acids 1-29 form the signal peptide, 30-278 represent LAP and the C-terminal amino acids from 279-390 form TGFβ.
TGFβ is expressed at the cell surface (e.g.
on Treg cells) as a highly glycosylated, furin-processed product in complex with the LAP protein. This complex does not have biological activity (so is a.k.a. latent TGFβ) and requires further processing to produce active TGFβ [4