Fig. 1. Outline of p24 proteins and constructs. (A) Alignment of the cytoplasmic tails of p24 proteins and mutants (except chimeras) used in this study. White box: double-phenylalanine motif potentially involved in COP-II binding; gray box: positively charged amino acids, which are proposed to be involved in COP-I binding and retention in the early biosynthetic pathway. We termed p28 a novel putative member of the p24 family identified as a human gene evolutionarily conserved in Caenorhabditis elegans by comparative proteomics (accession number: Q9Y3A6). Tp24 was originally named putative T1/ST2 receptor binding protein (see Emery et al., 2000). (B) Schematic representation of p23 and p25 chimera used in this study. LD, lumenal domain; TM, transmembrane domain; CT, cytoplasmic tail. Domains of p23 are in light gray, CD4 in dark gray, and p25 in white.