No abstract

PDC-109 (13 kDa) is the most abundant component, and the major heparin-binding protein, of bovine (Bos taurus) seminal plasma. Here, we show that PDC-109 contains a single O-linked oligosaccharide (NeuNAc a(26)-Galp(l-3)-GalNAc-) attached to Thr". Immunoquantitation of PDC-109 indicates that its concentration in seminal plasma is 15-20 mg/ml. Though PDC-109 is not present on epididymal sperm, ejaculated spermatozoa on average are coated with (9.5 f 0.3) x IO6 molecules of PDC-109/tell. This value remained constant in swim-up sperm and decreased to (7.7 + 0.4) x lO%permatozoon after incubation for 24 h in capacitation medium at 39°C. These data substantiate the hypothesis that PDC-109 may be one of the seminal plasma components that enhance the fertilizing capacity of bull spermatozoa upon interaction with heparin-like glycosaminoglycans present in the female genital tract.

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The behaviour of nucleotides with thioketo‐substituted pyrimidine bases (4‐thiouracil, 2‐thiouracil and 2‐thiocytosine) or amino‐analogue purine bases (2‐aminopurine and 2,6‐diaminopurine) in transcription and translation was investigated. The experimental results obtained led to the following conclusions. The stereochemical basis of substrate selection in transcription is the geometry of Watson‐Crick base pairs A · U (or A · T) and G · C between substrate and template bases. The topology of the active site of Escherichia coli RNA polymerase is precisely adopted to the geometry of Watson‐Crick base pairs. The enzyme active site discriminates between A·U (A · T) and G · C base pairs. An essential feature in this discrimination is the 6‐NH2 group of the A · U (A · T) base pair and the 2‐keto group of cytosine in the G · C base pair. The codon properties of a nucleic acid base in messenger RNA can be predicted on the basis of its specificity in polynucleotide interactions. There seems to be no evidence for the participation of protein topological sites in the control of the specificity of codon‐anticodon interactions in translation.

Three cDNA clones, pHGR122, pHGR11, and pHGR74 containing the coding information for abundant mRNAs were identified from a human ovarian granulosa cell cDNA library. Characterization by nucleotide sequencing revealed that pHGR122 was specific for a collagenase inhibitor and pHGR11 for melanoma-associated antigen ME491. Relative quantification by Northern analysis indicated that collagenase inhibitor mRNA is a major species in granulosa cells. This finding provides evidence for the origin of this protein in follicular fluid as a secretory product of granulosa cells. pHGR11 identified melanoma-associated antigen ME491 as the unexpected product of normal, noncarcinogenic, granulosa cells. pHGR74 has the complete coding information for an unknown protein. Three independent experiments: (i) cell-free translation of pHGR74 RNA; (ii) transcription of suitable restriction fragments followed by cell-free translation; (iii) hydrolysis of the cell-free translation product of pHGR74 RNA by endoproteinase Lys-C, identified one open reading frame coding for an acidic, highly hydrophilic protein of 111 amino acid residues. pHGR74 mRNA is expressed in human testis, prostate, seminal vesicle, and ovarian granulosa cells. A comparative Southern analysis indicates pHGR74 mRNA is species specific and encoded by a single-copy gene.