Complete amino acid sequence of mouse prolactin

Area of Science:

• Biochemistry
• Molecular Biology
• Endocrinology

Background:

• Prolactin is a crucial hormone involved in reproduction and lactation.
• Understanding the primary structure of prolactin is essential for elucidating its function.
• Comparative analysis with related hormones can reveal conserved and unique structural features.

Purpose of the Study:

• To establish the complete primary amino acid sequence of mouse prolactin.
• To identify the locations of disulfide bonds within the mouse prolactin structure.
• To investigate amino acid residues critical for the lactogenic activity of mouse prolactin.

Main Methods:

• Peptide mapping using tryptic digestion and cyanogen bromide treatment.
• Enzymatic cleavage with Staphylococcus aureus protease.
• Amino acid sequencing via manual liquid-phase and solid-phase Edman degradation.
• Comparative sequence analysis with other prolactins and related hormones.

Main Results:

• The complete primary structure of mouse prolactin was elucidated.
• Three disulfide bonds were assigned: Cys-4-Cys-9, Cys-56-Cys-172, and Cys-189-Cys-197.
• A unique replacement of tryptophan at position 89 with serine was observed, differing from other growth hormones.
• Asp-18, His-25, Ser-60, and Thr-63 were identified as potentially essential for lactogenic activity.

Conclusions:

• The primary structure of mouse prolactin has been fully characterized.
• Specific amino acid residues are implicated in the hormone's biological function.
• The findings provide insights into the structure-activity relationship of prolactin and related hormones.