Molecular cloning and sequence analysis of the human ribosomal protein S16

Abstract

A cDNA library from a poorly differentiated human pancreatic tumor cell line was screened for differentially expressed mRNAs using single-stranded cDNA probes synthesized from poly(A+) RNA of the poorly differentiated cell line Panc 1 and a very well differentiated cell line CD11. One of the cDNA clones isolated hybridized to a transcript size of 650 base pairs on Northern blot analysis and showed 30-fold higher expression in the poorly differentiated cell line as compared with the well differentiated cell line. Sequence analysis of this cDNA clone and its deduced amino acid sequence showed an open reading frame of 441 nucleotides with 100 and 98.6% homology to ribosomal protein S16 (rpS16) from rat and mouse, respectively. Northern blot analyses with a panel of 14 pancreatic cell lines, 2 breast cell lines, 2 colon cell lines, and several other tissues showed higher expression of rpS16 only in the poorly differentiated pancreatic tumor cell line Panc 1. The expression of mRNA for two other ribosomal proteins, rpL30 and rpL32, were not elevated in Panc 1. Southern blot analysis of genomic DNA showed a 20-fold amplification of a single band among the rpS16 family only in the Panc 1 cell line.