In our effort to identify orphan HIF like proteins in the data base that are potential targets of the pVHL complex , we report multiple splice variants of the human HIF 3 alpha locus as follows : hHIF 3 alpha 1 , hHIF 3 alpha 2 ( also referred to as hIPAS ; human inhibitory PAS domain protein ) , hHIF 3 alpha 3 , hHIF 3 alpha 4 , hHIF 3 alpha 5 , and hHIF 3 alpha 6 . ^^^