Nucleic Acids Research, 1988, Vol. 16, No. 18 8803-8815
© 1988
Articles |
Oocyte and somatic 5S ribosomal RNA and 5S RNA encoding genes in Xenopus tropicalis
Max-Planck-Institut für Molekulare Genetik, Otto-Warburg-Laboratorium Ihnestrasse 73, D-1000 Berlin 33 1Freie Universität Berlin, Institut für Biochemie Thielallee 63, D-1000 Berlin 33 2Freie Universität Berlin, Institüt fur Molekularbiologie and Biochemie Arnimallee 22, D-1000 Berlin 33, FRG
Received June 24, 1988. Revised August 22, 1988. Accepted August 22, 1988.
We have investigated the structure of oocyte and somatic 5S ribosomal RNA and of 5S RNA encoding genes in Xenopus tropicalis. The sequences of the two 5S RNA families differ in four positions, but only one of these substitutions, a C to U transition in position 79 within the internal control region of the corresponding 5S RNA encoding genes, is a distinguishing characteristic of all Xenopus somatic and oocyte 5S RNAs characterized to date, including those from Xenopus laevis and Xenopus borealis. 5S RNA genes in Xenopus tropicalis are organized in clusters of multiple repeats of a 264 base pair unit; the structural and functional organization of the Xenopus tropicalis oocyte 5S gene is similar to the somatic but distinct from the oocyte 5S DNA in Xenopus laevis and Xenopus borealis. A comparative sequence analysis reveals the presence of a strictly conserved pentamer motif AAAGT in the 5'-flanking region of Xenopus 5S genes which we demonstrate in a separate communication to serve as a binding signal for an upstream stimulatory factor.