Antibodies induced against mammalian single-stranded DNA binding protein (ssDBP) UP I were shown to be cross-reactive with most of the basic hnRNP core proteins, the main constituents of 40S hnRNP particles. This suggested a structural relationship between both groups of proteins. Using the anti-ssDBP antibodies, a cDNA clone (pRP10) was isolated from a human liver cDNA library in plasmid expression vector pEX1. By DNA sequencing this clone was shown to encode in its 949 bp insert the last 72 carboxy terminal amino acids of the ssDBP UP I. Thereafter, an open reading frame continued for another 124 amino acids followed by a UAA (ochre) stop codon. Direct amino acid sequencing of a V8 protease peptide from hnRNP core protein A1 showed that this peptide contained at its amino terminus the last 11 amino acids of UP I followed by 19 amino acids which are encoded by the open reading frame of cDNA clone pRP10 immediately following the UP I sequence. This proves that ssDBP UP I arises by proteolysis from hnRNP core protein A1. This finding must lead to a re-evaluation of the possible physiological role of UP I and related ssDBPs. The formerly assumed function in DNA replication, although not completely ruled out, should be reconsidered in the light of a possible alternative or complementary function in hnRNA processing where UP I could either be a simple degradation product of core protein A1 (as a consequence of controlling the levels of active A1) or may continue to function as an RNA binding protein which has lost the ability to interact with the other core proteins.(ABSTRACT TRUNCATED AT 250 WORDS)
This research output has an Altmetric Attention Score of 6. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 20 April 2026.
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#27
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Altmetric has tracked 34,518,147 research outputs across all sources so far. This one has received more attention than most of these and is in the 73rd percentile.
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