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The NIF3L1 protein is strongly conserved during evolution from bacteria to mammals and recently its function in neuronal differentiation has been demonstrated. In the present study we identified novel binding partners of human NIF3L1 by screening a HeLa cDNA-library using the yeast two-hybrid system. We could show that the NIF3L1 protein is interacting with itself and with the NIF3L1 binding protein 1 (NIF3L1 BP1), a novel protein of 23.67kDa bearing a putative leucine zipper domain. Furthermore, both interactions were confirmed using the mammalian two-hybrid system. Deletion analyses clearly demonstrated that a C-terminal region of 100 amino acids of the NIF3L1 BP1 is sufficient for the interaction with NIF3L1. The NIF3L1 BP1 is ubiquitously expressed and cotransfection experiments revealed that NIF3L1 and NIF3L1 BP1 interact in the cytoplasm of human LNCaP cells. This study provides novel insights into the cellular function of the NIF3L1 protein.

The genes Phf5a and Phf5b-ps are the first two members of a novel murine multigene family that is highly conserved during evolution and belongs to the superfamily of PHD-finger genes. The Phf5 gene family contains an active locus on mouse chromosome 15, region E and several processed pseudogenes on different chromosomes. The active locus, Phf5a, is expressed ubiquitously in pre- and postnatal murine tissues and encodes a protein of 110 amino acids. The protein is localized in the nucleus in a non-homogenous pattern as the nucleolar subcompartment is almost free of Phf5a. The molecular and biological functions of Phf5a are unknown up-to-date, but the systematic deletion of its yeast homolog is lethal, pointing out that the protein is required for cell viability. Interpretation of our data and review of the literature suggest both basic and essential cellular functions of the Phf5a protein, possibly acting as a chromatin-associated protein., (Copyright 2002 Elsevier Science (USA).)

In the article by Hiramoto et al. (1997) (Stage-specific expression of a mouse homologue of the porcine 135 kDa alpha-d-mannosidase (MAN2B2) in type A spermatogonia, Biochem. Biophys. Res. Commun. 241, 439-445) a new homologue to the porcine epididymis-specific 135 kDa alpha-d-mannosidase (MAN2B2) was cloned from a mouse testis cDNA library. Northern blot analysis with RNA of different tissues showed a testis-specific expression by using a mouse MAN2B2 oligonucleotide. In situ hybridization revealed that the mouse MAN2B2 transcript is localized exclusively in spermatogonia. In consequence to this it was proposed by Hiramoto et al. that the mouse MAN2B2 homologue could serve as a marker for spermatogonia. By repeating the published experiments we observed a different expression pattern of the mouse MAN2B2 gene. Northern blot analysis with either testicular RNA from prepubertal males or with testicular RNA from the W/W(v)-mutant mouse which lacks germ cells showed an expression of the MAN2B2 gene. Furthermore, Northern blot analysis with RNA from different somatic tissues revealed that the gene is ubiquitously expressed. Therefore, our refinement clearly demonstrates that the MAN2B2 mouse homologue is not specifically expressed in spermatogonia., (Copyright 2000 Academic Press.)