Latent TGF‐β binding protein‐3 (LTBP‐3) requires binding to TGF‐β for secretion

Abstract
Latent transforming growth factor‐β (TGF‐β) binding protein (LTBP)‐1, which is easily secreted, has been shown to enhance the secretion of TGF‐β. Here we show that another member of the LTBP family, LTBP‐3, is not secreted by several cell types, but secretion occurs after coexpression with TGF‐β. The secretion of LTBP‐3 requires complexing of LTBP‐3 with Cys33 of the TGF‐β propeptide.