FIGURE 1:

Identification of IGPR-1 as a novel cell surface glycoprotein. (A) The deduced amino acid sequence of human IGPR-1. Amino acids 1–22 are a putative signal sequence (underlined). The immunoglobulin domain of IGPR-1 is shown (red), together with a proline-rich cytoplasmic region. (B) Orthologues of IGPR-1 in various species. (C) The predicted immunoglobulin domain of IGPR-1, which is based on the Ig domain of myelin-associated glycoprotein. IGPR-1 was cloned into retroviral vector (pMSCV), and PAE cells were transduced with viruses of empty vector or IGPR-1. (D) Whole-cell lysates derived from PAE cells were subjected to Western blot analysis using anti-IGPR-1 antibody. (E) Whole-cell lysates derived from PAE cells expressing IGPR-1 were either untreated or treated with PNGase and immunoblotted with anti-IGPR-1 antibody. (F) Immunofluorescence microscopy of PAE cells expressing IGPR-1. (G) PAE cells expressing IGPR-1 were subjected to cell surface biotinylation as described in Materials and Methods, and biotinylated IGPR-1 was detected by blotting with an anti–streptavidin-horseradish peroxidase antibody. (H) The same membrane was reblotted with anti–IGPR-1.