Latent TGF beta 1 cDNA encodes a 390 amino acid precursor that contains a 29 aa signal peptide and a 361 aa proprotein 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 beta 1 Disulfide linked homodimers of LAP and TGF beta 1 remain non covalently associated after secretion forming the small latent TGF beta 1 complex