Insertion of an HERV(K) LTR in the intron of NBPF3 is not required for its transcriptional activity.

The NBPF genes are members of a recently described gene family that has an intricate genomic organization. These genes can be subdivided into two subfamilies based on the presence of an intronic HERV(K) LTR insertion in the 5' region. A recent report describes a functional implication for this insertion, claiming that only NBPF genes with this insertion are transcriptionally active [Illarionova, A.E., Vinogradova, T.V., Sverdlov, E.D., 2007. Only those genes of the KIAA1245 gene subfamily that contain HERV(K) LTRs in their introns are transcriptionally active. Virology, 358 (1): 39-47]. Here, we show that an NBPF gene lacking this insertion, NBPF3, is expressed in a variety of tissues. Thus the effect of HERV(K) LTR insertion on NBPF gene expression remains unknown.