Vitellogenin diversity in tropical lizards (Anolis pulchellus): identification and partial characterization

1. Three size-classes of vitellogenin polypeptides were detected by electrophoretic and radiolabeling techniques in 32Pi-labeled plasma of vitellogenic female lizards but not in male animals. Based on their apparent Mr, the polypeptides were designated as VTG-226-201K, VTG-169-153K and VTG-116-123K. 2. Structural differences were found between VTG-169-153K and VTG-116K by partial proteolysis with S. aureus V8 protease and radiolabeling techniques. 3. Autoradiography of a 3-10% native gradient gel revealed three different species of VTG in 32Pi-labeled plasma of stimulated males: VTG-I (Mr = 850,000), VTG-II (Mr = 750,000) and VTG-III (Mr = 610,000). By 2D PAGE, it was shown that VTG-169K and VTG-116K are components of VTG-I, while VTG-153K and VTG-116K comprise VTG-III. These results suggest an oligomeric structure for native VTG. 4. Amino acid analysis, 32Pi incorporation, electrophoretical behavior and Mr estimation demonstrated homology between VTG-116K and the S1-lipovitellin from the lizard egg. 5. These results strongly indicate an unusual multiplicity of VTG forms in tropical lizards when compared to other egg-laying vertebrates.