Fig. 1. Comparison of amino acid sequences and temporal expression patterns of Xenopus EGF-CFC factors. (A) Comparison of the amino acid sequences of Xenopus EGF-CFC proteins (XCR1, XCR2, XCR3S and XCR3L). XCR3L has a 72 amino acid insertion following the signal sequence of XCR3S. Dash indicates no amino acid present. Identical residues are shadowed. Conserved EGF-like domains and CFC domains are underlined. Cysteine residues in the additional 72 amino acids of XCR3L are indicated by asterisks. (B) Temporal expression patterns of Xenopus EGF-CFC genes (XCR1, XCR2, XCR3S and XCR3L) detected by RT-PCR. RNA was extracted from embryos at the stages indicated over each lane. XCR3S (lower band) and XCR3L (upper band) were detected using a set of primers designed to span the insert region. Both bands showed a similar temporal expression pattern. e, un-fertilized egg; RT-, RT-PCR reaction without reverse transcriptase.