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Primary structure of equine pituitary prolactin
S R Lehrman1, H W Lahm, M C Miedel
1Department of Protein Biochemistry, Roche Research Center, Hoffmann-La Roche Inc., Nutley, NJ.
International Journal of Peptide and Protein Research
|June 1, 1988
Summary
Equine prolactin, a protein hormone, shares high sequence homology with porcine and fin whale prolactins. This study suggests prolactin evolves faster than growth hormone.
Area of Science:
- Biochemistry
- Molecular Biology
- Comparative Genomics
Background:
- Prolactin is a crucial hormone involved in reproduction and lactation across mammals.
- Understanding the primary sequence of equine prolactin provides insights into mammalian hormone evolution.
Purpose of the Study:
- To determine the primary amino acid sequence of equine prolactin.
- To compare the equine prolactin sequence with other known prolactin sequences.
- To investigate the evolutionary rate of prolactin compared to growth hormone.
Main Methods:
- Automated Edman analyses of S-carboxymethylated equine protein.
- Proteolytic fragmentation of modified equine prolactin.
- Sequence homology analysis with other mammalian prolactins.
- Comparison of evolutionary changes with equine growth hormone.
Main Results:
- Equine prolactin is a 199-amino acid single-chain protein with conserved cysteine and tryptophan residues.
- Highest sequence homology was observed with porcine (93%) and fin whale (87-91%) prolactins.
- Equine prolactin shows a higher rate of evolutionary change (17/199 residues) compared to equine growth hormone (4/191 residues).
- Approximately 60% of equine prolactin is predicted to form alpha helices.
Conclusions:
- Equine prolactin sequence is closely related to other mammalian prolactins, particularly porcine.
- Prolactin appears to evolve at a faster rate than growth hormone, supporting evolutionary divergence theories.
- The predicted secondary structure of equine prolactin is consistent with experimental data.