Highly conserved lipoprotein assembly in teleost and amphibian yolk-platelet crystals

Abstract

Yolk platelet crystals in the frog, Xenopus laevis, are orthorhombic (space group P21221) and consist of elongated asymmetric units (.apprx.5.5 .times. 11.5 .times. 25 nm). The presence of an orthorhombic lattice in amphibian yolk platelets fulfilling the symmetry requirements of crystals was missed in earlier structural interpretations. Here, a comparative study of teleost [Pelvicachromus pulcher], urodele [Triturus sp.] and anuran [Rana temporaria] yolk platelet crystals showed the widespread occurrence among aquatic vertebrates of an orthorhombic lattice with unit-cell sides similar to those of Xenopus. The space group (P212121) and certain features of the macromolecular complex are at variance with those reported for Xenopus.