Carp preproinsulin cDNA sequence and evolution of insulin genes

Area of Science:

• Molecular Biology
• Evolutionary Biology
• Biochemistry

Background:

• Insulin plays a crucial role in glucose metabolism across vertebrates.
• Understanding insulin gene structure provides insights into evolutionary adaptations.
• Carp (Cyprinus carpio) serves as a model for studying freshwater teleostean insulin.

Purpose of the Study:

• To determine the complete nucleic acid sequence of carp preproinsulin cDNA.
• To analyze the deduced amino acid sequence of carp preproinsulin, including signal peptide and C-peptide.
• To investigate evolutionary relationships of carp insulin compared to other vertebrates.

Main Methods:

• Cloning of carp preproinsulin cDNA into the pBR322 plasmid.
• DNA sequencing of the cloned insert (439 bp).
• Bioinformatic analysis of nucleotide and deduced amino acid sequences.

Main Results:

• The complete coding sequence for carp preproinsulin (108 amino acids) was determined.
• Confirmation of the previously established carp insulin amino acid sequence.
• Identification of the signal peptide (21 amino acids) and C-peptide (35 amino acids).
• Observed variations in signal peptide length and B-chain suggest a shifted signal peptidase cleavage site.
• Comparative analysis indicated a significant evolutionary distance between freshwater and saltwater teleosts.

Conclusions:

• The determined carp preproinsulin cDNA sequence provides a comprehensive genetic resource.
• Structural variations in carp preproinsulin suggest adaptive evolutionary changes in processing.
• Evolutionary divergence between freshwater and saltwater teleosts is comparable to that between mammals and birds.