The growth hormone receptor interacts with its sheddase, the tumour necrosis factor-alpha-converting enzyme (TACE)

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Abstract
Proteolysis of the GHR (growth hormone receptor) occurs at the cell surface and results in the release of its extracellular domain, the GHBP (growth hormone-binding protein). TACE (tumour necrosis factor-α-converting enzyme) has been identified as a putative protease responsible for GHR cleavage. However, GHR–TACE interaction has not been observed until now. Here, we identified TACE in Chinese hamster cells and confirmed processing and cell-surface expression. Interaction between GHR and TACE was only observed after growth hormone binding. As the growth hormone–GHR2 complex is a poor substrate for TACE, we conclude that the GHR–TACE interaction precedes proteolysis, and is transient. Furthermore, we demonstrate that TACE is present in endosomes, where it partly co-localizes with endocytosed growth hormone ligand.