Post-translational assembly of lens alpha-crystallin in the reticulocyte lysate and in Xenopus laevis oocytes.
Lens mRNA was translated in reticulocyte lysate predominantly into monomeric alpha-crystallin chains. Lens polyribosomes added to the cell-free system produced the same polypeptides, but these were detected predominantly in alpha-crystallin aggregates. Lens mRNA, after microinjection into Xenopus laevis oocytes, produced alpha-crystallin subunits that were exclusively found in the form of high-molecular-weight complexes. Also after injection of the purified 14-S mRNA, coding for the alphaA subuint, the synthesized alpha-A polypeptides were incorporated into high-molecular-weight aggregates. In contrast, the synthesis of alphaB subunits, directed by a 10-S mRNA, did not result in aggregate formation. The experiments thus suggest that aggregate formation of alpha-crystallin is triggered by its alphaA subunits, which are then joined by the alphaB subunits. This process occurs partly in the cell-free system and completely in Xenopus oocytes.
D000818:Animals; D002417:Cattle; D003459:Crystallins / Q000096:biosynthesis*; D005260:Female; D007908:Lens, Crystalline / Q000378:metabolism; D046911:Macromolecular Substances; D008970:Molecular Weight; D009865:Oocytes / Q000378:metabolism*; D010063:Ovum / Q000378:metabolism*; D011132:Polyribosomes / Q000378:metabolism; D011233:Precipitin Tests; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D012156:Reticulocytes / Q000378:metabolism*; D014981:Xenopus
D003459:Crystallins; D046911:Macromolecular Substances; D012333:RNA, Messenger