PLASMATOCYTE SPREADING PEPTIDE IS ENCODED BY AN MESSENGER-RNA DIFFERENTIALLY EXPRESSED IN TISSUES OF THE MOTH PSEUDOPLUSIA-INCLUDENS

It has long been known that blood cells (hemocytes) are an essential c omponent of the invertebrate immune system, yet little is known about the molecules mediating their function. Recently, we identified plasma tocyte spreading peptide (PSP1) from the moth Pseudoplusia includens w hich regulates the trafficking and adhesion of a hemocyte subclass cal led plasmatocytes. Here, we report the cloning of a cDNA (p15) that en codes a PSP1 precursor protein. Northern blot analysis revealed that a homologous prepro-PSP1 mRNA is expressed in fat body, and that other PSP1-related transcripts are expressed in nervous tissue and hemocytes . Coupled in vitro transcription/translation reactions indicated that p15 produces a protein recognized by a PSP1 polyclonal antibody. Immun oblotting experiments further revealed that a putative pro-PSP1 protei n is present in P. includens plasma and fat body. (C) 1998 Academic Pr ess.