QR1 (QR1)

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QR1, named from the cDNA, QR1, cloned from the neuroretina of quail, Coturni. coturnix has 676 residues. Its C-terminal portion is similar to the extracellular glycoprotein, BM40. QR1 and BM40 are the only examples of (normally) extracellular EF-hands proteins. "Transcription of QR1 takes place only during the late phase of retinal development and is shut off sharply at hatching." [49].