They are encoded by closely linked genes, yet each gene is regulated differently so that each protein in the family is expressed on a different range of cell types. In particular, differentiating white blood cells may display one or other, or several of these molecules depending on which type of white blood cell it is becoming, and on how mature it is. Some of the Ly-6 family are expressed at high levels on lymphocytes and some other types of cell when they are influenced by interferons, which are regulatory proteins produced during infections. These are a new family of regulatory peptides which modulate cell growth, and which may be most important in tissue replacement and wound healing. We are now also studying granulins in the nematode C. elegans , since we found a 3-domain precursor encoded in the C. elegans genome.
Antimicrobial peptides are also under study.
Such peptides from distant species may turn out to be of therapeutic value. But we are interested also in additional regulatory roles these peptides may have. Neutrophil defensins, for example, are released from cells upon binding microorganisms, and some members of the defensin families in several species have been shown to have other activities such as stimulating the opening of cell membrane calcium channels. Shan, X., Bourdeau, A., Rhoton, A., Wells, D. E., Cohen, E. H., Landgraf, B. E. and Palfree, R.G.E. 1998. Bhandari, V., Palfree, R.G.E. and Bateman, A. 1992.