Production and Characterization of Specific Anti-peptide Antiserum Against Free α-subunit of Rat Pituitary Glycoprotein Hormones

Abstract

To obtain an antibody specific for the α-subunit of rat pituitary glycoprotein hormones, we synthesized a peptide corresponding to the sequence 37–53 (ST-7: Phe-Ser-Arg-Ala-Tyr-Pro-Thr-Pro-Ala-Arg-Ser-Lys-Lys-Thr-Met-Leu-Val) of the rat α-subunit. The polyclonal antiserum against this peptide was generated in rabbits. This region is hydrophilic and highly conserved among several mammalian species. Noncompetitive binding tests showed that the ST-7 antiserum had specific affinity for the rat free α-subunit, but not for rat intact LH, FSH, and TSH. The ST-7 antiserum immunostained two types of cells in the rat anterior pituitary, i.e., gonadotrophs and thyrotrophs. This was also the case in mouse, cattle, sheep, and pig, which have an identical sequence of ST-7 in their α-subunit. The pituitary cells of horse (Arg substituted for Lys as residue 48 of the rat α-subunit), human, and eel (Leu for Ala at residue 45), chicken (Met for Ala at residue 45), and bullfrog (Tyr for Phe at residue 37 and Met for Ala at residue 45) were not stained with the ST-7 antiserum. This study indicated that the ST-7 antiserum is sequence-specific for the α-subunit and is therefore useful for immunohistochemical studies on the secretory pathway of the free α-subunit.