Studies on the relative rates of intracellular transport of egg white proteins

In order to determine if the rates of intracellular transport of oviduct secretory proteins are coordinate, oviduct minces were first incubated with either [3H]methionine or [3H]leucine. 2 h later, the minces were exposed to either [35S]methionine or [14C]leucine in addition to the 3H-labeled amino acid. After incubating for an additional 90-120 min, aliquots of the media were subjected to immunoprecipitation to isolate ovalbumin, conalbumin and lysozyme. From the 3H/35S or 3H/14C ratios in the isolated proteins, relative rates of intracellular transport were determined. The data obtained indicate that conalbumin and lysozyme exhibit similar rates of intracellular transport, whereas ovalbumin lags behind these proteins considerably. The basis for this effect is discussed in light of current knowledge concerning the synthesis and secretion of ovalbumin.