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

Abstract

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