Human growth hormone binds to lactogenic receptors in bovine, ovine and rat adrenals

The distribution of 125I radioactivity in the liver, kidneys, adrenals and serum of male rats was measured 10 minutes after an intravenous bolus of 125I-labelled human growth hormone (hGH) was administered in the presence or absence of a large excess of ovine growth hormone or ovine prolactin. The hGH binding sites in the adrenals had displacement properties characteristic of lactogenic receptors, whereas those in the liver had displacement properties characteristic of somatogenic receptors. Bovine and ovine adrenal microsomal membrane fractions contained high affinity (Ka = 1.4-3.3 nM-1) binding sites for hGH which showed ligand specificity typical of lactogenic receptors. It is concluded that the hGH binding site in the adrenal gland is a classical lactogenic receptor and that this tissue is a convenient and rich (42.6 +/- 6.4 fmol hGH specifically bound/mg protein) source of receptor suitable for further characterization.     

Diversity of puroindolines as revealed by two-dimensional electrophoresis

Puroindolines are endosperm lipid binding proteins, which are separated by reversed phase-high-performance liquid chromatography or cation exchange chromatography into two isoforms, puroindoline-a (PIN-a) and puroindoline-b (PIN-b). Being very basic and close in molecular weight, PIN-a and PIN-b have never been separated using conventional isoelectric focusing and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). A two-dimensional electrophoresis method, linear immobiline pH gradient (IPGxSDS-PAGE), was developed, using 6-11 linear immobiline Dry Strips in the first dimension, which allowed the puroindolines to be focused between isoelectric point 10.5 and 11. Immunoblotting revealed that both PIN-a and PIN-b were each composed of several spots. Two-dimensional patterns from unrelated wheat varieties revealed that several spots can be highlighted among varieties. Matrix-assisted laser desorption/ionization-time of flight spectrometry allowed the majority of the spots revealed in the puroindoline zone to be identified. The two-dimensional IPGxSDS-PAGE of these very basic wheat endosperm proteins, puroindolines and related grain softness proteins should facilitate the identification of the proteins associated with wheat endosperm texture that have a strong effect on milling, dough properties and end-uses of wheats.     

Genetic differences among several species of Tricladida from the relict Lake Ohrid as revealed by enzyme electrophoresis

Six endemic and two widely distributed species living in Lake Ohrid were studied. In general, these hermaphroditic animals displayed no signs of departure from Hardy-Weinberg equilibrium. Genetic variation in all but one of the endemic species was of the same extent as that in geographically wide ranging invertebrates. On the other hand, the Lake Ohrid population of the common European species Dendrocoelum lacteum was monomorphic at all loci examined. D. sanctinaumi, one of the endemic species, exhibited a clear genetic subdivision into spring and littoral subpopulations. The genetic differentiation of Crenobia alpina alpina and C. a. montenigrina proved commensurable to that of well separated species from other genera. The data suggest that the separation of particular lineages in the set of Lake Ohrid endemics was widely dispersed over time.     

Involvement of lysine residues in the binding of ovine prolactin and human growth hormone to lactogenic receptors

The lactogenic activity (L.A.) of oPRL and hGH derivatives obtained by chemical modifications of lysine residues was studied by radioreceptor assay. Control treatment with borohydride had a slight effect on the L.A. of hGH but drastically reduced the oPRL activity; this latter was preserved in the presence of iodoacetamide. Methylation, ethylation, guanidination and acetimidination affected the L.A. of both hormones as a function of the degree of modification. The structure-binding relationships to the lactogenic receptors are discussed, suggesting that the lysine or arginine residues in homologous positions 42, 51, 73, 128, 146 of oPRL and 47, 50, 73, 128, 147 of hGH might be particularly involved.     

Capillary zone electrophoresis of insulin and growth hormone

The separation power of capillary zone electrophoresis was examined using highly purified and well-characterized biosynthetic human insulin, growth hormone, their derivatives, and related proteins. Mixtures of proteins were chosen to illustrate practical applications of this technique. Proteins differing slightly in structure, but equivalent in net charge, were not completely separated. Degradation of insulin by dilute acid treatment was followed by capillary zone electrophoresis, native polyacrylamide gel electrophoresis, and reversed-phase liquid chromatography. Excellent correlation was observed between these techniques. Simple equipment requirements and analysis times on the order of 10 min make capillary zone electrophoresis attractive for analytical protein separations.     

Species relationships and genetic variation in the diploid wheats (Triticum,Aegilops) as revealed by starch gel electrophoresis

Twenty enzyme loci were examined in the diploid species ofTriticum andAegilops for allelic variation by starch gel electrophoresis. SectionSitopsis, including the five species,Ae. speltoides, Ae. lingissima, Ae. sharonensis, Ae. bicornis andAe. searsii form a close subgroup withAe. speltoides slightly removed from the others.T. monococcum s. lat., was found to be closest to the species of theSitopsis group.Ae. comosa, Ae. umbellulata andAe. uniaristata form a second subgroup withAe. caudata most closely related to these species.Ae. squarrosa appears almost equally related to all of the species, showing no special affinity for any one species group. Nineteen out of twenty loci examined were polymorphic with a mean of 6.7 alleles per locus. Species could be, for most loci, characterized by the presence of predominant alleles. A conspicious genetic characteristic ofTriticum-Aegilops is the sharing of these predominant alleles between species. Within species variation is characterized by a diffuse distribution of secondary alleles.