Placement of small lipovitellin subunits within the vitellogenin precursor in Xenopus laevis.

N-terminal amino acid sequence data for the small lipovitellin subunits in Xenopus laevis crystalline yolk platelets indicate that LV2 beta is derived from vitellogenin A2 and that LV2 tau is most likely derived from vitellogenin A1. The small lipovitellin subunits apparently commence within the exon 24 region of the parental vitellogenins, flanking the C-terminal end of phosvitin. As a consequence, we conclude that most of the vitellogenin sequence encoded by exons 30 to 35 is not accounted for by the known yolk proteins.