FIG. 1.

Schematic of Krp1. Krp1 is a type I membrane protein with an N-terminal presequence (diagonal lines), a single transmembrane domain (wavy lines), and a short cytoplasmic domain (residues 696 to 709). The residues at the end of the prosequence are shown to highlight the location of the primary (Lys-Arg102) and internal (Lys-Arg82) cleavage sites. The locations of residues used to truncate Krp1 are also indicated (Y611, R667, and K696). There are five potential sites for N glycosylation (lollipops) and a Ser/Thr-rich region (light shading just N terminal of the transmembrane domain) with several potential sites for O glycosylation. The catalytic domain contains the active-site residues (Asp, His, Asn, and Ser) and is followed by the P domain (dark shading), a region of high sequence homology between members of the kexin family (15); residues near the predicted C terminus of the P domain are shown for comparison. S. pombe (Sp) Krp1 (8), Saccharomyces cerevisiae (Sc) Kex2 (10), Kluyveromyces lactis (Kl) Kex1 (46), Mus musculus (Mm) PC6 (33), Homo sapiens (Hs) PACE4 (20), Drosophila melanogaster (Dm) fur1 (36), Dm fur2 (37), Hs PC2 (43), Hs PC3 (= PC1) (44), Hs PC7 (= PC8) (3), Hs fur1 (48), X. laevis (Xl) fur1 (21), and Mm PC4 (34) sequences are shown. AAs, amino acids.