A gene that is related to SRY and is expressed in the testes encodes a leucine zipper-containing protein.
SRY-related cDNA encoding a protein with a high-mobility-group (HMG) box and a leucine zipper motif, which was designated SOX-LZ, was isolated from a rainbow trout testis cDNA library. Comparison of this cDNA with the mouse homologous cDNA isolated from a testis cDNA library exhibits an overall amino acid sequence identity of 77%, which is in striking contrast to the abrupt loss of amino acid sequence homology outside the HMG box found among mammalian SRY genes. In both rainbow trout and mice, Northern (RNA) blot analyses have revealed the presence of a testis-specific 3-kb-long SOX-LZ mRNA, and this transcript appeared coincidentally with the protamine mRNA, suggesting its expression in the germ line. A recombinant HMG box region protein encoded by SOX-LZ could bind strongly with an oligonucleotide containing an AACAAT sequence, which is also recognized by mouse Sry and Sox-5. Upon cotransfection into CHO cells, SOX-LZ transactivated transcription through its binding motif when the region including the leucine zipper motif was deleted [SOX-LZ (D105-356)]; however, the intact SOX-LZ failed to transactivate. The intact SOX-LZ could form homodimers through the leucine zipper, which resulted in inhibition of DNA binding by the HMG box, while SOX-LZ (D105-356), which was incapable of dimerization, showed specific binding with the AACAAT sequence. Thus, the repressed transactivation of the intact SOX-LZ in CHO cells was primarily attributable to the low level of DNA binding of SOX-LZ homodimers.
Takamatsu
N
N
Department of Biosciences, School of Science, Kitasato University, Kanagawa, Japan.
Kanda
H
H
Tsuchiya
I
I
Yamada
S
S
Ito
M
M
Kabeno
S
S
Shiba
T
T
Yamashita
S
S
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D029941:Fish Proteins; D005786:Gene Expression Regulation; D008040:Genetic Linkage; D006609:High Mobility Group Proteins / Q000235:genetics*; D016350:Leucine Zippers; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D017686:Oncorhynchus mykiss / Q000235:genetics* / Q000254:growth & development; D010802:Phylogeny; D011485:Protein Binding; D011487:Protein Conformation; D012333:RNA, Messenger / Q000302:isolation & purification; D012045:Regulatory Sequences, Nucleic Acid; D055747:SOX Transcription Factors; D017386:Sequence Homology, Amino Acid; D012733:Sex Differentiation / Q000235:genetics; D051876:Sex-Determining Region Y Protein; D013737:Testis / Q000737:chemistry* / Q000254:growth & development; D014157:Transcription Factors; D015533:Transcriptional Activation; D014998:Y Chromosome / Q000235:genetics
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; D029941:Fish Proteins; D006609:High Mobility Group Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D055747:SOX Transcription Factors; D051876:Sex-Determining Region Y Protein; C497746:Sry protein, mouse; D014157:Transcription Factors