Fig. 4.

Secretion profiles of C-terminal domain swap constructs. (A) Constructs used to investigate the roles of the C-terminal cbEGF domains in fibrillin-1 secretion and microfibril binding. Domains cbEGF32-34, which lack the ability to interact with the fibrillin-1 N-terminal domains and fold autonomously (16), are highlighted in red where they have replaced cbEGF41-43. (B) Deletion of domains cbEGF41-43 (Δ41–43) results in intracellular retention of fibrillin-1. This could not be salvaged by replacing cbEGF41-43 with cbEGF32-34 (32-34-swap). Deleting the last two domains from 32-34swap (34X) rescued secretion.