1.A.96 The Polyoma Virus Viroporin (PVVP) Family The agnoprotein viroporin (Suzuki et al. 2010) alters the structure of the nuclear envelope by interacting with host CBX5, disrupting CBX5 associations (Okada et al. 2001) and transporting Ca²⁺ (Hyser and Estes 2015). It is involved in the perinuclear-nuclear localization of the capsid protein VP1 during virion assembly and maturation. It also plays a role in the release of progeny virions from infected cells and in viral propagation by acting as a viral ionic channel in the host plasma membrane. It mediates influx of extracellular calcium ions in the host cell and may contribute to viral genome transcription and translation of viral late proteins (Suzuki et al. 2010). Virus-host protein interactions allow the host to regulate viroporin activity and suggest that viroporins may be regulated by specific interactions with host cell proteins (Suzuki et al. 2013).
References:
Hyser, J.M. and M.K. Estes. (2015). Pathophysiological Consequences of Calcium-Conducting Viroporins. Annu Rev Virol 2: 473-496.
Okada, Y., S. Endo, H. Takahashi, H. Sawa, T. Umemura, and K. Nagashima. (2001). Distribution and function of JCV agnoprotein. J Neurovirol 7: 302-306.
Scott, C. and S. Griffin. (2015). Viroporins: structure, function and potential as antiviral targets. J Gen Virol 96: 2000-2027.
Suzuki, T., Y. Orba, Y. Makino, Y. Okada, Y. Sunden, H. Hasegawa, W.W. Hall, and H. Sawa. (2013). Viroporin activity of the JC polyomavirus is regulated by interactions with the adaptor protein complex 3. Proc. Natl. Acad. Sci. USA 110: 18668-18673.
Suzuki, T., Y. Orba, Y. Okada, Y. Sunden, T. Kimura, S. Tanaka, K. Nagashima, W.W. Hall, and H. Sawa. (2010). The human polyoma JC virus agnoprotein acts as a viroporin. PLoS Pathog 6: e1000801.
Examples:
TC#	Name	Organismal Type	Example
1.A.96.1.1	*Agnoprotein viroporin of 71 aas and 1 TMS (Suzuki et al.* 2010). It is cation-selective, capable of Ca²⁺ accomodation, and is involved in particle production (Scott and Griffin 2015).**		Agnoprotein of human polyoma JC virus

1.A.96.1.2	Agnoprotein of 90 aas and 2 TMSs.		Agnoprotein of Simian virus 40 (SV40)

1.A.96.1.3	Agnoprotein of 68 aas and 1 TMS		Agnoprotein of Yellow baboon polyomavirus 2