Chemical and Immunological Properties of Iodocompounds Associated with Particulate Fractions of Hog Thyroid Cells

抄録

Iodocompounds bound with various particulate components in hog thyroid cells were analyzed quantitatively with their chemical and immunological properties based on the iodine analysis of the particulate components and their detergent extracts. Almost all the particle-bound iodine was found to be protein-bound and distributed among various sized particulate components. Sodium deoxycholate (0.26% to 1%) solubilized about 80% of the iodoprotein from either microsomal or lysosomal fraction and about 60% of that from either mitochondrial or nuclear fraction. Addition of 0.5% sodium dodecyl sulfate into 1% sodium deoxycholate caused the solubilization of particle-bound iodoprotein (s) remaining after the sodium deoxycholate treatment. Sixty percent of the microsomal or of the lysosomal iodoproteins solubilized with sodium deoxycholate was precipitated with anti-hog thyroglobulin serum in a “double” immunoprecipitation system, while 40% of the mitochondrial or the nuclear iodoproteins was precipitated. From these analyses, it was concluded that at least 80% of thyroglobulin-related iodoproteins in the particulate fractions was associated with rather small particulate components in the cell homogenate. Analysis by sucrose density gradient centrifugation showed that 50% of the protein-bound iodine solubilized from the microsomal pellet was recovered in 19 S region, suggesting the presence of an appreciable amount of particle-bound thyroglobulin with similar sedimentation property to “soluble” thyroglobulin.