OLIVA, R., 1995. - Sequence, evolution and transcriptional regulation of avian-mammalian P1 type protamines. In: JAMIESON, B. G. M., AUSIO, J., & JUSTINE, J.-L. (eds), Advances in Spermatozoal Phylogeny and Taxonomy. Mém. Mus. natn. Hist. nat., 166 : 537-548. Paris ISBN : 2-85653-225-X.

Methodological approaches to protamine P1 sequence determination have evolved from the initial protein sequencing methods to the robust cloning and PCR-based techniques. Twenty-seven different mammalian-avian P1 type protamine genes and 32 different P1 amino-acid sequences are now available and allow detailed phylogenetic analysis and the study of transcriptional control mechanisms. All mammalian-avian P1 type protamines contain a well conserved N-terminus with the consensus "ARYR" followed by alternating "S/T-S-S" phosphorylatable residues. Eutherian mammalian P1s contain cysteine residues, whereas birds, prototherian and metatherian protamines lack cysteine. Thus cysteine appeared after the divergence of marsupials, monotremes and placental lineages. Overall detailed phylogenetic analysis of the gene sequences indicates that the evolution of P1 genes is in agreement with the expected species evolution supporting that these genes have evolved vertically.

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