Near-full-length REV3L appears to be a scarce maternal factor in Xenopus laevis eggs that changes qualitatively in early embryonic development.
REV3 is the catalytic subunit of DNA polymerase zeta (pol zeta), which is responsible for the damage-induced mutagenesis that arises during error-prone translesion synthesis in eukaryotes. The related REV3L genes in human and mouse encode proteins of approximately 350kDa, twice as large as yeast REV3, but full-length REV3L has not been identified in any vertebrate cell. We report that Xenopus laevisREV3L encodes a 352-kDa protein that has high overall amino acid sequence similarity to its mammalian counterparts, and, for the first time in a vertebrate species, we have detected putative REV3L polypeptides of 300 and 340kDa in X. laevis oocytes. Only the 300-kDa form is stored in eggs, where its concentration of about 65pM is much lower than those of other replication and repair proteins including the accessory pol zeta subunit REV7. In fertilized eggs, the levels of this polypeptide did not change until neurula; the larger 340-kDa form first appeared at stages after gastrula, suggesting a pattern of regulation during development. These observations indicate the existence of REV3L as a scarce protein, of approximately the full predicted size, whose level may impose severe constraints on the assembly of pol zeta in X. laevis.
Ogawara
Daichi
D
Division of Molecular Biology, Graduate School of Biological Sciences, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma, Nara, Japan.
Muroya
Taketo
T
Yamauchi
Kazumi
K
Iwamoto
Taka-aki
TA
Yagi
Yoshihiko
Y
Yamashita
Yoshihiro
Y
Waga
Shou
S
Akiyama
Masahiro
M
Maki
Hisaji
H
D000818:Animals; D018076:DNA, Complementary / Q000235:genetics / Q000302:isolation & purification; D004259:DNA-Directed DNA Polymerase / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D009865:Oocytes / Q000378:metabolism*; D011485:Protein Binding; D013997:Time Factors; D029867:Xenopus Proteins / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis / Q000196:embryology* / Q000235:genetics / Q000378:metabolism*
D018076:DNA, Complementary; D029867:Xenopus Proteins; C425929:DNA polymerase zeta; D004259:DNA-Directed DNA Polymerase