Table 1. Identification of SPF proteins in axolotl courtship and male water.

N-terminal sequences were obtained by Edman degradation. Sequences of the 20-25 kDa protein bands exhibit a cysteine pattern (indicated in bold as 'x') typical for SPF proteins. The x's designate residues for which no signal was detected and usually represent unmodified cysteines that cannot be detected by Edman degradation (cysteines were not alkylated prior to the sequence analysis). Low sequencing signals close to the level of background are indicated in grey. Transcripts obtained by RACE-PCR that correspond to one of the N-terminal sequences are indicated.