Phyto-Amp is a family of phytopathogenic wall-less bacterial antigenic membrane proteins [1]. The bacteria are limited to the phloem and pose a major threat to agriculture worldwide. They are transmitted in a persistent, propagative manner by phloem-sucking Hemipteran insects. Phytoplasma membrane proteins are in direct contact with hosts and are assumed to be involved in determining vector specificity. Phyto-Amp is thought to be one family of proteins that mediates such specificity. The proteins appear to be encoded by circular extrachromosomal elements, at least one of which is a plasmid [2].

1: Immunodominant membrane proteins from two phytoplasmas in the aster yellows clade (chlorante aster yellows and clover phyllody) are highly divergent in the major hydrophilic region. Barbara DJ, Morton A, Clark MF, Davies DL; Microbiology. 2002;148:157-167. PMID:11782508

2: The major antigenic membrane protein of "Candidatus Phytoplasma asteris" selectively interacts with ATP synthase and actin of leafhopper vectors. Galetto L, Bosco D, Balestrini R, Genre A, Fletcher J, Marzachi C; PLoS One. 2011;6:e22571. PMID:21799902