Identification and characterization of novel rat and human gonad-specific organic anion transporters.
We have isolated three novel organic anion transporter cDNAs designated rat GST-1 (gonad-specific transporter), rat GST-2, and human GST, expressed at high levels in the testis. Rat GST-1, GST-2, and human GST consist of 748, 702, and 719 amino acids, respectively, and all molecules possess the 12 predicted transmembrane domains, which is a common structure of organic anion transporters. Northern blot analyses and in situ hybridization revealed that both of the rat molecules are highly expressed in the testis, especially in Sertoli cells, spermatogonia, and Leydig cells. Weak signals are also detected in the epididymis and ovary in adult rat. The exclusive expression of human GST mRNA in the testis was confirmed by RT-PCR. The pharmacological experiments of Xenopus laevis oocytes injected with the respective rat GST-1- and GST-2-cRNAs revealed that both rat GST-1 and GST-2 transport taurocholic acid, dehydroepiandrosterone sulfate, and T4 with Michaelis-Menten kinetics (taurocholic acid, Km = 8.9 and 2.5 microm, dehydroepiandrosterone sulfate, Km = 25.5 and 21.microm, and T4, Km = 6.4 and 5.8 for rat GST-1 and GST-2, respectively). T3 was also transported by rat GST-1 and GST-2. These data suggest that rat GST-1 and GST-2 might be one of the molecular entities responsible for transporting dehydroepiandrosterone sulfate and thyroid hormones involved in the regulation of sex steroid transportation and spermatogenesis in the gonad.
Suzuki
Takehiro
T
Division of Nephrology, Endocrinology, and Vascular Medicine, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan.
Onogawa
Tohru
T
Asano
Naoki
N
Mizutamari
Hiroya
H
Mikkaichi
Tsuyoshi
T
Tanemoto
Masayuki
M
Abe
Michiaki
M
Satoh
Fumitoshi
F
Unno
Michiaki
M
Nunoki
Kazuo
K
Suzuki
Masanori
M
Hishinuma
Takanori
T
Goto
Junichi
J
Shimosegawa
Tooru
T
Matsuno
Seiki
S
Ito
Sadayoshi
S
Abe
Takaaki
T
D000595:Amino Acid Sequence; D000818:Animals; D003687:Dehydroepiandrosterone / Q000378:metabolism; D005260:Female; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D007985:Leydig Cells / Q000502:physiology; D008297:Male; D008969:Molecular Sequence Data; D009865:Oocytes / Q000502:physiology*; D009928:Organ Specificity; D027361:Organic Anion Transporters / Q000235:genetics* / Q000378:metabolism*; D051381:Rats; D017386:Sequence Homology, Amino Acid; D012708:Sertoli Cells / Q000502:physiology; D013656:Taurocholic Acid / Q000378:metabolism; D013737:Testis / Q000502:physiology*; D013974:Thyroxine / Q000378:metabolism; D014982:Xenopus laevis
D003687:Dehydroepiandrosterone; D027361:Organic Anion Transporters; D013656:Taurocholic Acid; D013974:Thyroxine; C487009:SLCO6A1 protein, human; C487007:gonad-specific transporter-1, rat; C487008:gonad-specific transporter-2, rat