A Prolactin-Inducible T Cell Gene Product Is Structurally Similar to theAspergillus nidulansNuclear Movement Protein NUDC

Clone 15 (c15) was originally identified as a PRL-inducible gene in activated T cells. Sequence analysis of c15 revealed that the last 94 amino acids of c15 are 68% identical and 78% similar to the filamentous fungus Aspergillus nidulans nuclear movement protein NUDC. The identification of the mammalian (rat) c15 protein suggests that the carboxy-terminal NUDC-like region has been conserved over evolution for an important structure and/or function. To determine whether c15 is functionally analogous to NUDC, complementation studies were performed using the inducible/repressible pAL5 vector system. The results of the complementation experiments show that the full-length mammalian c15 protein is not only capable of rescuing the nuclear movement defect of the nudC3 mutants, but is also able to restore the expression of the downstream endogenous NUDF protein to near wild type levels. These results indicate that rat c15 and fungal NUDC not only share similar structures, but also serve similar functions. Taken together, the structural and functional conservation between c15 and NUDC is consistent with the notion that c15 is the rat homolog of nudC and has therefore been given the name RnudC.