The Transmembrane Protein Tango1 Is a Packaging Protein That Helps

The transmembrane protein Tango1 is a packaging protein that helps some secretory proteins leave the endoplasmic reticulum (ER) after synthesis. Knocking down Tango1 by RNA interference impairs the incorporation of collagen VII, but not collagen I, into transport vesicles destined for the Golgi apparatus. The protein contains a lumenal N-terminal SH3 domain and a cytosolic C-terminal proline-rich domain. Which of the following proteins would you expect to interact with the N-terminal and C-terminal domains of Tango1, respectively?

A) Procollagen VII; COPI components
B) Procollagen VII; COPII components
C) Procollagen I; COPI components
D) Procollagen I; COPII components
E) COPI components; procollagen I