NSP 5a3a's link to nuclear-cyto proteins B23 and hnRNP-L between normal and aberrant breast cell lines.

NSP 5a3a had been identified along with three other distinct though similar isoforms corresponding to locus HCMOGT-1 on chromosome 17p11.2. ( 1) Secondary structure analysis of the NSP isoforms revealed similarity to Spectrin and Spectrin like proteins containing coiled coil domains. ( 1) These proteins have been implicated and found to be involved in a plethora of cellular activities ranging from intracellular trafficking, cellular and subcellular integrity ( 2, 3) to being involved in protein-protein interactions with other structural proteins as well as involved in protein complex stabilization and scaffolding thus facilitating homo or hetero dimerization of protein complexes. ( 4) The NSP 5a3a isoform had been identified to be highly expressed in-vitro in particular cancer cell lines while very low to null in normal body tissues. ( 1) Subsequent investigation of this isoform revealed its novel interaction with B23 ( 5) , a known nucleolar protein involved in ribosome biogenesis, rRNA transcription, mitosis, cell growth control, and apoptosis. ( 6) We have since then, further elucidated its potential involvement in cellular processes such as ribosome biogenesis and rRNA processing by confirming and establishing NSP 5a3a's novel interaction with B23 and ribonuclear protein hnRNP-L, respectively thus possibly implicating NSP 5a3a in cellular processes such as ribosome biogenesis and rRNA transcription . Finally, an intriguing differential cooperation between these proteins has been observed in both normal and cancer breast cell models and additionally through siRNa silencing, we have found hnRNP-L as a potential novel regulator of NSP 5a3a.