Identification of the spinal degradation products and inhibition of adenylate cyclase by recombinant rat galanin message-associated peptide.

In rat preprogalanin, galanin is C-terminally flanked by a 60 amino acid long peptide: galanin message-associated peptide (GMAP). GMAP sequences in different species show high degree of homology, suggesting a biological role. However, the study of the physiological and pharmacological actions of this peptide have been hampered by lack of availability of this large peptide, its fragments and well-characterized antibodies to GMAP. This study report the production of GMAP in Escherichia coli and the use of the recombinant peptide to define its degradation products in the spinal cord. The GMAP fragments formed upon incubation of GMAP with membranes of lumbar spinal cord were identified by sequencing and were also produced by solid phase synthesis for studies on second messenger systems. Furthermore, the study demonstrates that GMAP inhibits forskolin stimulated adenylate cyclase activity in a concentration dependent manner, while GMAP and its synthetic fragments did not affect cGMP level.