Hormonotoxins. Effects of modifying the gonadotropin alpha-subunit on the generation of lutropin-toxin conjugates.
On the basis of the observation that in the hormonotoxin oLH-gelonin conjugation of the toxin occurs via the alpha-subunit of lutropin, an attempt was made to develop a general method for generation of similar hybrid proteins involving other glycoprotein hormones. In this approach sites suitable for conjugation would be first introduced into the alpha-subunit, hybridized with any native hormone specific beta-subunit of choice (LH-beta, FSH-beta, TSH-beta) following which the toxic component gelonin would be added on in the form of gelonin-S-S-alpha---beta complex. Thus, thiolated lutropin alpha-subunit recombined well with free lutropin beta-subunit, yielding a hybrid which was active in terms of receptor binding, immunoreactivity, and steroidogenic properties. However, subsequent conjugation with thiolated gelonin, a ribosome inactivating protein, resulted in dissociation of beta-subunit from its non-covalent union with the thiolated alpha-subunit. It is concluded that the addition of positively charged gelonin at particular sites on the alpha-subunit led to the destabilization of the lutropin quaternary structure.
Singh
V
V
Reproduction Research Laboratory, Clinical Research Institute of Montreal, Quebec, Canada.
Sairam
M R
MR
D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D005260:Female; D006062:Gonadotropins / Q000378:metabolism; D006107:Granulosa Cells; D007986:Luteinizing Hormone / Q000378:metabolism; D010940:Plant Proteins / Q000378:metabolism; D010944:Plants / Q000378:metabolism; D011487:Protein Conformation; D051381:Rats; D011987:Receptors, Steroid / Q000378:metabolism; D011994:Recombinant Proteins; D054789:Ribosome Inactivating Proteins, Type 1; D013388:Succinimides; D014118:Toxins, Biological
D006062:Gonadotropins; D010940:Plant Proteins; D011987:Receptors, Steroid; D011994:Recombinant Proteins; D054789:Ribosome Inactivating Proteins, Type 1; D013388:Succinimides; D014118:Toxins, Biological; C058542:luteinizing hormone-gelonin conjugate protein, plant; C018151:N-succinimidyl 3-(2-pyridyldithio)propionate; C025674:GEL protein, Gelonium multiflorum; D007986:Luteinizing Hormone