Chapter 7, Problem 46P

Antibodies were made that recognize six proteins that are part of a complex inside the Caenorhabditis elegans one-cell embryo. The mother produces proteins that are believed to assemble stepwise into a structure in the egg, beginning at the embryo’s inner surface. The antibodies were used to detect the protein location in embryos produced by mutant mothers [who are homozygous recessive for the gene(s) encoding each protein]. The C.elegans mothers are self-fertilizing hermaphrodites, so no wild-type copy of a gene will be introduced during fertilization.

In the following table, * means the protein was present and at the embryo surface, − means that the protein was not present, and + means that the protein was present but not at the embryo surface. Assume all mutations prevent production of the corresponding protein.

Complete the following figure, which shows the construction of the hypothetical protein complex, by writing the letter of the proper protein in each circle. The two proteins marked with arrowheads can assemble into the complex independently of each other, but both are needed for the addition of subsequent proteins to the complex.