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

Ohlendorf et al. have reported that yolk-platelet crystals in the frog, Xenopus laevis, were orthorhombic (space group P21221) and consisted of elongated asymmetric units (approximately 5.5 x 11.5 x 25 nm). The presence of an orthorhombic lattice in amphibian yolk platelets fulfilling the symmetry requirements of crystals had been missed in earlier structural interpretations. A comparative study of teleost, urodele and anuran yolk-platelet crystals performed in our laboratory has shown the widespread occurrence among equatic vertebrates of an orthorhombic lattice with unit-cell sides similar to those of Xenopus. However, we report here that the space group (P212121) and certain features of the macromolecular complex are at variance with those reported for Xenopus.