Ubiquitination of the human immunodeficiency virus type 1 Env glycoprotein

Expression of the human immunodeficiency virus type 1 (HIV-1) Env glycoprot ein is stringently regulated in infected cells, The majority of the glycopr otein does not reach the cell surface but rather is retained in the endopla smic reticulum or a cis-Golgi compartment and subsequently degraded. We her e report that Env of various HIV-1 isolates is ubiquitinated at the extrace llular domain of gp41 and that Env expression could be increased by lactacy stin, a specific proteasome inhibitor, suggesting that the ubiquitin/protea some system is involved in control of expression and degradation.