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The primary structure of sturgeon prolactin: phylogenetic implication
T Noso1, C S Nicoll, A L Polenov
1Laboratory of Molecular Endocrinology, School of Fisheries Sciences, Kitasato University, Iwate, Japan.
General and Comparative Endocrinology
|July 1, 1993
Summary
The sturgeon prolactin (PRL) amino acid sequence was determined, revealing it is the largest known PRL. This fish PRL retains three disulfide bonds, a feature common in tetrapod PRLs.
Area of Science:
- Biochemistry
- Evolutionary Biology
- Comparative Endocrinology
Background:
- Prolactin (PRL) is a key hormone regulating reproduction and osmoregulation.
- The evolutionary history of PRL structure across vertebrate lineages remains incompletely understood.
- Chondrostean fishes, like sturgeon, represent an early diverging group of ray-finned fishes.
Purpose of the Study:
- To determine the complete amino acid sequence of sturgeon (Acipenser gueldenstaedti) prolactin.
- To compare the structural features of sturgeon PRL with those of other vertebrate PRLs.
- To infer the evolutionary changes in PRL structure during vertebrate evolution.
Main Methods:
- Pituitary gland extraction using acid-acetone.
- Purification via Sephadex G-25 gel filtration and reverse-phase high-performance liquid chromatography.
- Identification using immunoblot assays with anti-salmon and anti-ovine PRL antisera.
Main Results:
- The sturgeon PRL sequence comprises 204 amino acid residues, the longest reported for any PRL.
- Sturgeon PRL possesses three disulfide bonds, similar to tetrapod PRLs.
- Sequence identity was higher with teleost PRLs (35-46%) than tetrapod PRLs (30-40%).
Conclusions:
- Sturgeon PRL exhibits unique structural characteristics, including a large size and conserved disulfide bonding pattern.
- The findings suggest that an ancestral ray-finned fish PRL had three disulfide bonds.
- The loss of an amino-terminal disulfide bond likely occurred after the divergence of Chondrostei from other teleosts.