Identification and characterization of three isotypes of protein phosphatase inhibitor-2 and their expression profiles during testis maturation in rats.
cDNAs for three isotypes of inhibitor-2(I-2), I-2 alpha 1, I-2 alpha 2 and I-2 beta were isolated from a rat testis library. I-2 alpha 2 and I-2 beta are new forms. The former is an alternatively spliced form of I-2 alpha 1, encoding a protein with substitution of three amino acids for 14 amino acids of the I-2 alpha 1 protein at the C-terminus. The latter is derived from a different gene and encodes a 126-amino-acid protein having highly conserved regions with the I-2 alpha 1 protein from amino acid positions 22-47 and 111-126. I-2 alpha 2 and I-2 beta are expressed exclusively in the testis, and the expressions of all three forms of I-2 coincide with sperm cell maturation. The half-maximal inhibitory concentration of the GST-I-2 alpha 2 fusion protein on the PP1 gamma 2 catalytic subunit is the same as that of GST-I-2 alpha 1, being 10 nM. However, the half-maximal inhibitory concentration of GST-1-2 beta is 100-fold higher, being 1 microM. GST-I-2 beta showed no competition with GST-I-2 alpha 1. and its biological significance is unknown.
Osawa
Y
Y
Carcinogenesis Division, National Cancer Center Research Institute, Tokyo, Japan.
Nakagama
H
H
Shima
H
H
Sugimura
T
T
Nagao
M
M
D000595:Amino Acid Sequence; D000818:Animals; D018076:DNA, Complementary / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic; D008297:Male; D008969:Molecular Sequence Data; D010749:Phosphoprotein Phosphatases / Q000037:antagonists & inhibitors*; D011506:Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D051381:Rats; D015183:Restriction Mapping; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013737:Testis / Q000201:enzymology*; D014018:Tissue Distribution; D000097847:Protein Phosphatase Inhibitory Proteins
D018076:DNA, Complementary; D010749:Phosphoprotein Phosphatases; D011506:Proteins; C024833:protein phosphatase inhibitor-2; D000097847:Protein Phosphatase Inhibitory Proteins