H. Linden et al., THE TRH-LIKE PEPTIDES IN RABBIT TESTIS ARE DIFFERENT FROM THE TRH-LIKE PEPTIDE IN THE PROSTATE, FEBS letters, 379(1), 1996, pp. 11-14
Human seminal fluid contains a number of tripeptide amides with simila
r structures to thyrotropin releasing hormone (TRH), two of which have
been identified as pGlu-Glu-Pro amide and pGlu-Phe-Pro amide, To dete
rmine whether these peptides originate in the same tissues and have th
e same molecular origin, TRH-immunoreactive peptides were extracted fr
om the prostate and testis of the rabbit, purified by ion exchange chr
omatography and HPLC, and identified by co-chromatography with H-3-lab
elled marker peptides, In addition, trypsin digestion was used to rele
ase TRH-like tripeptides from N-extended forms of these peptides, The
sole TRH-like peptide in the prostate was shown to be pGlu-Glu-Pro ami
de; it was not accompanied by a detectable amount of pGlu-Phe-Pro amid
e, The prostate also appeared to contain a very small amount of N-exte
nded forms of these peptides, In contrast to the prostate, the testis
contained high concentrations of N-extended forms of pGlu-Phe-Pro amid
e but essentially no tripeptide, The testis also contained N-extended
forms of two other neutral TRH-like peptides which were less hydrophob
ic than pGlu-Phe-Pro amide, Neither the prostate nor the testis contai
ned a significant amount of TRH, The results show that in the rabbit t
he TRH-like peptides pGlu-Glu-Pro amide and pGlu-Phe-Pro amide occur i
n different tissues and appear to be formed from different precursors.