Multiple polymorphic alpha- and beta-tubulin mRNAs are present in sea urchin eggs.
Multiple alpha- and beta-tubulin RNAs were found in the mature unfertilized eggs of the sea urchin Lytechinus pictus. The alpha-tubulin RNAs were polymorphic in number, size, and relative amounts in the eggs of different females. Five to seven different size classes [1.75-4.2 kilobases (kb)] were detected on RNA gel blots. All egg preparations contained variable amounts of 1.8- and 2.25-kb beta-tubulin RNAs, and a few of them contained an additional 2.9-kb beta-tubulin RNA. The total amount of alpha-tubulin RNA did not always parallel that of beta-tubulin RNA. A portion of all of the various alpha- and beta-tubulin RNAs were polyadenylylated. RNase H digestions ruled out the possibility that some of these RNAs represented a single transcript bearing different lengths of 3' poly(A). One class of alpha-tubulin RNAs (2.4-2.65 kb) was reduced to 2 kb by RNase H, suggesting the presence of internal oligo(A) regions. All of the egg beta-tubulin RNAs sedimented as free ribonucleoprotein particles. Only a small portion of the 1.75- to 3.6-kb alpha-tubulin RNAs, but most of the 4.2-kb alpha-tubulin RNA, were found on polysomes before fertilization. In the 30-min embryo, small amounts of each of the various alpha- and beta-tubulin RNAs were recruited onto polysomes. Thus, each of the multiple polymorphic alpha- and beta-tubulin RNAs in the egg represent translationally competent mRNA.
D000818:Animals; D005260:Female; D005786:Gene Expression Regulation; D008970:Molecular Weight; D010063:Ovum / Q000502:physiology*; D011061:Poly A / Q000378:metabolism; D011110:Polymorphism, Genetic; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics; D012617:Sea Urchins / Q000196:embryology / Q000235:genetics*; D014404:Tubulin / Q000235:genetics*
D012333:RNA, Messenger; D014404:Tubulin; D011061:Poly A