Occurrence and Molecular Weight of Rabbit Uterine “Blastokinin”

Bullock, D. W.; Connell, Kathleen M.

doi:10.1093/biolreprod/9.2.125

Cited by 34 publications

(3 citation statements)

References 21 publications

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“…DISCUSSION Our amino acid composition and sequence data verify the previous suggestions that native BK/UG is composed of two polypeptides held together in part by disulfide bridges (14,15). We further verified that BK/UG is devoid of tryptophan (14)(15)(16)(17) and that it contains only one histidine and one tyrosine residue in each polypeptide chain. Each of the four indepen- (T-6 T-3 0 dently prepared samples used in this study had similar total amino acid compositions, and the tryptic and chymotryptic peptides of each sample were similar both by amino acid content and by fingerprinting.…”

Section: Methodssupporting

confidence: 89%

Amino acid sequence of a progesterone-binding protein.

Popp¹,

Foresman²,

Wise³

et al. 1978

Proc. Natl. Acad. Sci. U.S.A.

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The amino acid sequence of blastokinin, also called uteroglobin, has been determined by a combined study of both the intact native molecule and the peptide fragments resulting from tryptic and chymotryptic digestions. Sequence analyses performed by automated methods and by sequential digestion with leucine aminopeptidase and carboxypeptidase Y demonstrate that blastokinin is a dimer of identical 69-amino acid subunits held together in parallel orientation by two disulfide bridges at positions 3 and 68. The polypeptide chains are further characterized by the absence of tryptophan residues and by single residues of histidine and tyrosine at positions 8 and 21, respectively. Six of eight amino acids, positions 17-24, near the progesterone binding site of blastokinin contain a hydroxyl group. Knowledge of the chemistry of this receptor site should allow better perspectives of the chemistry of molecules in normal tissues that are dependent on progesterone for growth and development, as -well as compounds that could act as cancer antagonists for endocrine therapy of hormone-dependent tumors. Blastokinin (1), also termed uteroglobin (2), is a low molecular weight protein that was first isolated from the uterine fluid of pregnant rabbits. The synthesis and secretion of this protein have been shown to increase during the first 6 days of pregnancy, accounting for-more. than 50% of the total uterine protein by day 6 (day 0 = coitus) (3-5). The increase in blastokinin/uteroglobin (BK/UG)t levels at a time when endogenous levels of progesterone were rising implied that a correlation may exist between these two events. Several reports demonstrated that exogenous progesterone was capable of inducing the synthesis of this protein (2, 6, 7). The recent finding that BK/UG in turn binds progesterone with high affinity (7-9) implies that BK/UG may serve as a carrier molecule for the same steroid that induces its synthesis. These facts not only make BK/UG unique but they also make a further study of its structure important. In the paper we present the primary structure for BK/UG, its possible physiological role(s), and the significance of knowing its structure as a hormone receptor. amide gel electrophoresis and a single immunoprecipitin band in agar immunodiffusion plates. Prior to chemical analyses, an additional purification step was performed by molecular sieving through a Sephadex G-25 column (1.9 X 95 cm) equilibrated with 10 mM HC1. Elution with the same buffer (flow rate, 2 ml/min) allowed BK/UG to elute with the void volume while salts and other low molecular weight contaminants were still migrating. Peak fractions of BK/UG, identified by absorbancy at 280 nm, were pooled and lyophilized. Four samples, each containing 7-14 mg of BK/UG, were isolated. One sample was digested by trypsin without further treatment. The disulfide bonds of cystine in the other three samples were reduced and aminoethylated (11) prior to digestion by trypsin or chymotrypsin. MATERIALS AND METHODSAmino acid analyses were performed with a Be...

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Section: Methodssupporting

confidence: 89%

Amino acid sequence of a progesterone-binding protein.

Popp¹,

Foresman²,

Wise³

et al. 1978

Proc. Natl. Acad. Sci. U.S.A.

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“…180 to oppose the effect of progesterone by decreasing the relative uteroglobin content (Bullock & Willen, 1974;Barfield et al, 1976;Bullock, 1977). During pregnancy of rabbits, highly elevated uteroglobin concentrations begin to fall after day 5, and the relative concentration of this protein in the uterine fluid declines to very low values by day 9, in spite of a continually rising serum progesterone content (Urzua et al, 1970;Bullock & Connell, 1973;Beier, 1974). With a specific radioimmunological assay, Mayol & Longenecker (1974) were able to detect uteroglobin as late as on day 12 of pregnancy, although in much lower concentrations than on day 5 or 6.…”

mentioning

confidence: 99%

Hormonal control of uteroglobin secretion in rabbit uterus. Inhibition of uteroglobin synthesis and messenger ribonucleic acid accumulation by oestrogen and anti-oestrogen administration

Kopu

Hemminki

Torkkeli

et al. 1979

Biochemical Journal

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Investigations were conducted to quantify activity of uteroglobin mRNA and secretion of uteroglobin in rabbit uterus after administration of progesterone and 5alpha-dihydrotestosterone, either alone or concomitantly with oestradiol-17beta and tamoxifen, a non-steroidal anti-oestrogen. Poly(A)-containing mRNA was isolated from the uterine tissue by extraction with phenol/chloroform, precipitation with ethanol and chromatography on oligo(dT)-cellulose. Cell-free translation in vitro of the poly(A)-containing mRNA was carried out in a wheat-germ lysate, and the product isolated by specific immuno-precipitation with anti-uteroglobin antiserum purified by affinity chromatography. Radioimmunoassay was utilized to determine uteroglobin content in the uterine flushings and tissue preparations. When given for 5 days, both progesterone (1mg/kg per day) and 5alpha-dihydrotestosterone (25mg/kg per day) elicited a marked induction of uteroglobin secretion, which was accompanied with accumulation of uteroglobin mRNA in the tissue. Concomitant administration of oestradiol-17beta (50mug/kg per day) or tamoxifen (12.5mg/kg per day) significantly decreased both progesterone- and 5alpha-dihydrotestosterone-induced uteroglobin secretion, with a parallel decrease in the uteroglobin-mRNA activity. The decline in the uteroglobin content of the uterine flushes brought about by oestradiol-17beta or tamoxifen administration was not due to inhibition of secretion of this protein by the endometrial cells, since a simultaneous decrease occurred in the tissue uteroglobin content. After a 5-day pretreatment with progesterone (1mg/kg per day), administration of oestradiol-17beta (50mug/kg per day) during the ensuing 4 days greatly accelerated the decay of the uteroglobin content in the uterine fluid.

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“…Uteroglobin (or blastokinin) is a specific protein produced by rabbit endometrium when stimulated by exogenous or endogenous progesterone (Schwick, 1965;Beier, 1968a, b;Krishnan & Daniel, 1967;Urzua, Stambaugh, Flickinger & Mastroianni, 1970;; Bullock & Connell, 1973). The protein is known to bind steroids, particularly progesterone (Urzua et al, 1970;Beato & Baier, 1975), and its role in early rabbit embryonic development may be that of a carrier protein for progesterone (Arthur, Cowan & Daniel, 1972;El Banna & Daniel, 1972a, b;Beato & Baier, 1975).…”

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confidence: 99%