Identification of ERGIC-53 as an intracellular transport receptor of α₁-antitrypsin

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Figure S1. Assessment of the human adult liver cDNA-YFP1 library. (A) The human adult liver cDNA-YFP1 library was constructed in pcDNA3(SfiI-linker-YFP1) vectors covering all three reading frames of YFP1. An illustration of the vector map, its DNA sequence (gray), and the corresponding translation product (black) is shown. Inserts of one or two base pairs (red boxes) were introduced between the SfiI restriction sites (blue) and the linker region (green line) to cover all three reading frames of YFP1 (black arrow). (B) 16 clones of the cDNA-YFP1 library were randomly picked and subjected to SfiI restriction digest, which releases the library inserts. Agarose gel electrophoresis shows that all clones contain an insert larger than ∼1 kb. (C) Sequence analysis was used to identify the inserts and to determine their integrity regarding the translation start codon, stop codon, and N-terminal ER targeting signal. Note that 6 of the 16 cDNA inserts contain their start but lack their stop codon, which allows the expression of functional prey–YFP1 fusion proteins. Secretory and membrane proteins are well represented in the library. The sequence of clone No. 2 could not be determined (nd).