Acylation of adenovirus type 12 early region Ib 18‐kDa protein

Abstract

The 1 I-kDa E 1 b protein in Ad 12-transformed rat cells and in Ad 12-infected human cells binds lipid strongly. The lipid is not removed by boiling in the presence of SDS or by extraction with methanol/chloroform. It is, however, dissociated from the protein by treatment with methanolic KOH suggesting that attachment is through an ester linkage. The acylated 18-kDa protein is detected only in the membrane fraction. Labelling cell surface proteins on Ad 12-transformed cells with [*ZSI]iodosulphanilic acid shows that some of the Ad 12 18-kDa El b protein is present on the outside of the cell. It is concluded that this protein is responsible for cell surface T-antigen activity. Adenovirus I2 Ad 12 El protein Tumor antigen Acylation Post-translational modification

The E1B 19K protein associates with lamins in vivo and its proper localization is required for inhibition of apoptosis

“…While it is reasonable to assume that proper localization of the E1B 19K protein is signi®cant for its function as an inhibitor of apoptosis, this has not been tested as the E1B 19K protein lacks a discreet membrane targeting domain and a simple deletion is insu cient to mislocalize the E1B 19K protein. Although the E1B 19K protein does not contain a membrane targeting domain or any signal sequences to classify it as a typical membrane protein (Chiou et al, 1994b), acylation sites at the N-terminal half of the protein which are palmitated and myristated has been proposed to play a role in the membrane association of the E1B 19K protein (Grand et al, 1985;McGlade et al, 1987). However, the sites of acylation have not been mapped and mutated to demonstrate their functional relevance.…”

Individual adenovirus E1B proteins induce transformation independently but by additive pathways

“…Other E1B mRNAs encode 84R, 156R and 93R proteins which share 79 amino-terminal residues with 496R (Anderson et al, 1984;Virtanen & Pettersson, 1985;Lewis & Anderson, 1987; S. Brown, D. Takayesu & P. E. Branton, unpublished results). 176R affects DNA stability (White & Stillman, 1987), is acylated (Grand et al, 1985;McGlade et al, 1987), and is phosphorylated at Ser 164 (McGlade et al, 1989). Mutations in 176R frequently yield a phenotype (termed cyt/deg) characterized by rapid cell lysis and degradation of viral and cellular DNA (Mak & Mak, 1983;Pilder et al, 1984;Subramanian et al, 1984;White et al, 1984).…”

Fatty Acylation of Proteins

“…However. cells transformed by the non-enveloped viruses Simian virus 40, adenovirus and with the enveloped Harvey routine sarcoma virus express early proteins which become acylated and are located in the plasma membrane of the infected cells [72][73][74][75]. where they may play a role in the process of cell transformation (see subsection IV-B).…”