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1.C.32 The Amphipathic Peptide Mastoparan (Mastoparan) Family

Mastoparans are 14 (sometimes 13 or 15) amino acyl residue, amphipathic, α-helical peptides present in the venom of hornets, wasps and yellow jackets. They exert numerous biological effects including (1) degranulation of mast cells, (2) G-protein receptor mimicry, (3) phospholipase A2 stimulation, and (4) inhibition of Golgi vesicle transport. They all increase bilayer permeability to hydrophilic solutes by forming short lived pores. Because they are too short to span the membrane as amphipathic α-helices (a configuration they assume when in association with membranes), it is thought that they form bundles of peptides in a so called 'barrel-stove' configuration. Pore formation has been demonstrated electrophysiologically as well as by demonstrating increased permeability to hydrophilic molecules and dyes. They also exhibit cytotoxicity, but certain amino acid substitutions reduce the activity (Irazazabal et al. 2016). Their actual transmembrane architecture is unknown.

The generalized transport reaction catalyzed by mastoparan pores is:

Small molecules (in) Small molecules (out)

This family belongs to the: Cecropin Superfamily.

References associated with 1.C.32 family:

Arbuzova, A and G. Schwarz (1999). Pore-forming action of mastoparan peptides on liposomes: a quantitative analysis. Biochim. Biophys. Acta. 1420: 139-152. 10446298
Arcisio-Miranda, M., M.P. Dos Santos Cabrera, K. Konno, M. Rangel, and J. Procopio. (2008). Effects of the cationic antimicrobial peptide eumenitin from the venom of solitary wasp Eumenes rubronotatus in planar lipid bilayers: Surface charge and pore formation activity. Toxicon. 51: 736-745. 18206199
Irazazabal, L.N., W.F. Porto, S.M. Ribeiro, S. Casale, V. Humblot, A. Ladram, and O.L. Franco. (2016). Selective amino acid substitution reduces cytotoxicity of the antimicrobial peptide mastoparan. Biochim. Biophys. Acta. 1858: 2699-2708. 27423268