Inhibin, a gonadal hormone capable of preferential suppression of pituitary follicle-stimulating hormone (FSH) secretion, has recently been purified. The major form of this protein is an a48 heterodimer encoded by two separate genes. In contrast to the FSH-suppressing action of the a,3 heterodimer, the 1831 homodimer stimulates FSH secretion. Earlier investigations on testicular (1, 2) and ovarian (3-6) proteins capable of differential suppression of follicle-stimulating hormone (FSH), but not luteinizing hormone (LH), secretion by the anterior pituitary gland have been followed by the recent isolation of inhibin from porcine (7-9) and bovine (10, 11) follicular fluid. Based on the amino acid sequence of these proteins, porcine (12), human (13), and bovine (14) MATERIALS AND METHODS Animals. Male and female Sprague-Dawley rats were obtained from Johnson Laboratories (Bridgeview, IL). Neonatal male rats (7-day-old) were maintained at 8 to 10 per lactating mother, whereas adult male rats were hypophysectomized at 60-70 days of age and then used at 7-10 days after operation. For theca-interstitial cell cultures, immature female rats were hypophysectomized at 21 days of age and used at 4 days after operation. In addition, theca explants were obtained from 30-day-old intact rats.

Sexual dimorphism in selected extragenital tissues is described with emphasis on the molecular basis of the differences. Testosterone rather than 5α -dihydrotestosterone appears to be the major intracellular androgen in organs other than skin and reproductive tract, but other steroid metabolites and their receptors are required to produce the diverse tissue differences observed in males and females. There is also evidence that multiple hormones from several endocrine glands are required to act in concert with androgens to produce and maintain their effects. Although many of the consequences of sexual dimorphism, such as body size and strength, have been evident for centuries, other differences between males and females such as disease incidence, response to drugs and toxins, and the metabolism and assimilation of dietary constituents have only recently been discovered.

We have isolated and sequenced cDNAs for corticosteroid binding globulin (CBG) Corticosteroid binding globulin (CBG) is the major transport protein for glucocorticoids in the blood of almost all vertebrate species (1), and >90% of the cortisol in human plasma is bound by this protein (2). The remaining fraction is distributed more evenly between albumin and the pool of nonprotein-bound or "free" steroid that is generally assumed to be biologically active (2, 3). In humans, CBG is an acidic, -58-kDa glycoprotein (4-6) comprising five N-linked oligosaccharide chains (7) that collectively represent -23% of the molecule by mass (6, 7). The binding site for natural glucocorticoids appears to be a hydrophobic pocket containing one of two cysteine residues that have been identified by amino acid composition analyses (8)(9)(10)(11). Apart from this information, and the identification of eight residues at the NH2 terminus of human CBG (5, 11), there is virtually no information about its primary structure or the location of its steroid binding site.Like many other plasma transport proteins, CBG is produced and secreted by hepatocytes (12), but has also been identified in a number of glucocorticoid responsive cells (2, 13), and may even interact directly with the plasma membranes of some cells (14,15). The objectives of this study were, therefore, to predict the amino acid sequence of human CBG from a cDNA and to determine whether tissues other than the liver possess the capacity to produce this protein. § METHODS cDNA Cloning. A monospecific rabbit antiserum for human CBG (6) was initially used to screen a Xgtll human liver cDNA library that was kindly provided by S. L. C. Woo (Baylor College of Medicine, Houston). The screening method was based on the technique described by Young and Davis (16), with the exception that peroxidase-labeled protein A was used to detect antibody-antigen complexes in the presence of the chromogenic substrate 4-chloro-1-naphthol. The recombinant phage isolated in this way were used to prepare plate lysates using NZC top agar (GIBCO). The phage were harvested and purified, and the cDNA inserts were excised and inserted into the EcoRI site of pBR322 according to Maniatis et al. (17). Plasmids containing CBG cDNAs were used to transform competent Escherichia coli (strain MM 294), and transformants were propagated in Luria broth in the presence of ampicillin and chloramphenicol to amplify the plasmid (17). Plasmids were isolated by the alkaline lysis method and purified using benzoylated-naphthoylated-DEAE cellulose (Sigma) according to Gamper et al. (18). The cDNAs were routinely excised from the plasmid and purified by polyacrylamide gel electrophoresis, prior to nick-translation with 32P-labeled dCTP (17).In an attempt to isolate a full-length CBG cDNA, the radiolabeled cDNA was employed to rescreen the library. Nitrocellulose filters (Schleicher & Schuell; BA85, 0.45-,um pore size) were used to transfer DNA and were hybridized with 2 x 106 dpm of the CBG cDNA probe per ml, in the pr...

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Testin I and testin II are the two molecular variants of testin that are synthesized and secreted by Sertoli cells in vitro. N-Terminal and partial internal amino acid sequence analysis of testin I and testin II reveals that these molecules are identical with the exception that testin II has three extra N-terminal amino acids of TAP compared to testin I. Studies using immunohistochemistry suggested that testin is a component of the specialized junctional complexes in the seminiferous epithelium and other tissues. Immunoreactive testin is localized not only at Sertoli-Sertoli and Sertoli-germ cell junctions, but also at sites of similar junctions in the liver, epididymis, kidney, and intestine. Other physiological studies have shown that the secretion of testin is tightly coupled to the presence of germ cells. In view of its possible role in germ cell development and its unique localization in the cell junction, the purpose of the present study was to determine the structure of testin by sequencing its full-length cDNA. Two synthetic degenerate oligonucleotides based on the N-terminal and an internal amino acid sequence were used for polymerase chain reaction (PCR) to obtain a 289-bp cDNA fragment. This PCR product was subsequently used to isolate a 1371-bp cDNA from a cDNA expression library constructed from Sertoli cell poly(A) RNA. This cDNA coded for a 333 amino acid peptide that starts with an ATG initiation codon from the 5' end and ends with a TGA termination codon located 245 nucleotides before the polyadenylation site. The deduced amino acid sequence indicates that testin contains a 16 amino acid signal peptide with two possible cleavage sites that yield 314 and 317 amino acids for testin I and testin II with calculated molecular weights of 36,029 and 36,299, respectively. Comparison of the entire coding region of testin with existing sequences at Genbank, EMBL, and Protein Identification Resource indicates that testin shares 58%, 57.4%, and 61% identity with rat, mouse, and human cathepsin L at the amino acid level, respectively. The positions of all of the 7 Cys residues and 8 of the 10 Trp residues in testin are conserved with respect to those present in cathepsin L. It is noted that Cys-122 in the predicted active site of cathepsin L was replaced with Ser-122 in testin. In view of the striking primary sequence homology between testin and cathepsin L, we assayed the proteolytic activity of testin using conditions known to activate cathepsin L.(ABSTRACT TRUNCATED AT 400 WORDS)