pNiXa, a Ni(2+)-binding protein in Xenopus oocytes and embryos, shows identity to Ep45, an estrogen-regulated hepatic serpin.
A Ni(2+)-binding protein (pNiXa, 45 kD, pI 8.5) discovered in Xenopus embryos, was isolated from oocytes. Based on amino acid sequences, pNiXa belongs to the serpin superfamily and shows identity to the cDNA sequence of Ep45, an estrogen-regulated hepatic serpin that contains an (HX)n-motif found in eukaryotic transcription factors. Nondenatured pNiXa, purified by Ni-affinity chromatography, inhibited bovine alpha-chymotrypsin. The presence of pNiXa in embryos when they are susceptible to Ni2+, the high avidity of pNiXa for Ni2+, and the (HX)n-motif point to pNiXa as a molecular target of Ni(2+)-teratogenesis.
Beck
B L
BL
Department of Laboratory Medicine, University of Connecticut School of Medicine, Farmington 06030.
Henjum
D C
DC
Antonijczuk
K
K
Zaharia
O
O
Korza
G
G
Ozols
J
J
Hopfer
S M
SM
Barber
A M
AM
Sunderman
F W
FW
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000378:metabolism; D005260:Female; D008297:Male; D008969:Molecular Sequence Data; D009532:Nickel / Q000378:metabolism*; D009865:Oocytes / Q000378:metabolism; D017385:Sequence Homology; D015842:Serine Proteinase Inhibitors / Q000737:chemistry / Q000378:metabolism; D015843:Serpins / Q000737:chemistry / Q000378:metabolism*; D013723:Teratogens / Q000378:metabolism; D029867:Xenopus Proteins; D014982:Xenopus laevis
D000596:Amino Acids; D002352:Carrier Proteins; D015842:Serine Proteinase Inhibitors; D015843:Serpins; D013723:Teratogens; D029867:Xenopus Proteins; C077804:SERPINA6 protein, Xenopus; D009532:Nickel