Nucleolar Preribosomal Associated Protein 1 (NPA1)

Npa1 accumulated in the immediate vicinity of the dense fibrillar component of the nucleolus in yeast. Npa1 was predominantly associated with the 27SA2 pre-rRNA, the RNA component of the earliest pre-60S ribosomal particles. Absence of Npa1 perturbed the pre-rRNA processing pathway leading to 5.8S and 25S rRNA. Npa1 interacted with 8 putative helicases as well as with other nucleolar factors.

The 3-prime UTR contains Alu sequences and other repetitive elements. RT-PCR detected highest NPA1 expression in kidney, followed by liver, skeletal muscle, prostate, ovary, heart, brain, placenta, lung, testis, pancreas, and spleen. Little to no expression was detected in thymus and small intestine.