Fig. 1. Xenopus p24 proteins and their relationship with p24 proteins from other species. (A) Alignment of members of the p24 protein family in X. laevis. Aligned are the amino acid sequences deduced from cDNA clones, the EST database entry BF611875 (representing Xp24₂) and the two p24 subfamily members identified previously (Kuiper et al., 2000). The cDNAs of the Xenopus p24 proteins have been isolated from a neurointermediate pituitary cDNA library, except for those of Xp24₂ and -₁ (isolated from an embryo library). Amino acids that are conserved in at least five sequences are in black boxes. The putative signal peptidase cleavage sites of the N-terminal signal sequences (incomplete for Xp24₂) are indicated by an arrow. Asterisks indicate the two conserved cysteine residues present in the lumenal domains of all p24 proteins. The predicted transmembrane region (TM) is underlined. (B) Phylogenetic tree of the p24 proteins from mouse (m), Xenopus (X), Drosophila melanogaster (d), Caenorhabditis elegans (c) and p24₁ from dog, and the classification in the four proposed p24 subfamilies. (C) Amino acid sequence identity (%) between p24 proteins of mouse and X. laevis. For sequence comparisons and phylogenetic tree construction, the p24 proteins without their signal sequences were aligned by the Clustal W algorithm using default parameters (AlignX program in Vector NTI Suite 6; InforMax, North Bethesda, MD). The mp24₁ protein lacks part of the N-terminal region (indicated with an asterisk). Sequences are mostly compilations of several data base entries and accession numbers are available upon request.

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