9.A.29 The Lantibiotic Immunity Protein/Serine Connector Protein (LIP/SIP) Family
LanG may or may not function with LanEF ( an ABC antibiotic exporter; TC 3.A.1.131.2) (Okuda et al., 2010).
HIV-1 Nef and the unrelated mouse leukaemia virus glycosylated Gag (glycoGag) proteins strongly enhance the infectivity of HIV-1 virions produced in certain cell types in a clathrin-dependent manner. Usami et al. 2015 showed that Nef and glycoGag prevent the incorporation of the multipass transmembrane proteins serine incorporator 3 (SERINC3; TC# 9.A.29.3.4) and SERINC5 into HIV-1 virions to an extent that correlates with infectivity enhancement. Silencing of both SERINC3 and SERINC5 precisely phenocopied the effects of Nef and glycoGag on HIV-1 infectivity. The infectivity of nef-deficient virions increased more than 100-fold when produced in double-knockout human CD4+ T cells that lacked both SERINC3 and SERINC5, and re-expression experiments confirmed that the absence of SERINC3 and SERINC5 accounted for the infectivity enhancement. Furthermore, SERINC3 and SERINC5 together restricted HIV-1 replication, and this restriction was evaded by Nef. SERINC3 and SERINC5 are highly expressed in primary human HIV-1 target cells, and inhibiting their downregulation by Nef is a potential strategy to combat HIV/AIDS (Usami et al. 2015).