Phosphorylation of human hnRNP protein A1 abrogates in vitro strand annealing activity (original) (raw)

Journal Article

Fabio Cobianchi ,

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Cinzia Calvio ,

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Monica Stoppini ,

1

Dipartimento di Biochimica, Universitá di Pavia

Via Tararnelli 3lb 27100 Pavia, Italy

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Massimo Buvoli ,

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Silvano Riva

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Received:

26 October 1992

Revision received:

19 January 1993

Accepted:

19 January 1993

Published:

25 February 1993

Cite

Fabio Cobianchi, Cinzia Calvio, Monica Stoppini, Massimo Buvoli, Silvano Riva, Phosphorylation of human hnRNP protein A1 abrogates in vitro strand annealing activity, Nucleic Acids Research, Volume 21, Issue 4, 25 February 1993, Pages 949–955, https://doi.org/10.1093/nar/21.4.949
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Abstract

In HeLa cells metabolically labeled in vlvo wlth [32P] orthophosphate in the presence of okadalc acid the concentration of phosphorylated A1 proteln was Increased slgnlflcantty as compared to controls. Purifled recombinant hnRNP protein A1 served as an excellent substrate in vitro for the catalytic subunit of cAMP-dependent proteln kinase (PKA) and for casein kinase II (CKII). Thin layer electrophoresls of A1 acld hydrolysates showed the proteln to be phosphorylated exclusively on serine residue by both kinases. V8 phosphopeptlde maps revealed that the target slte(s) of in vitro phosphorylatlon are located in the C-terminal reglon of A1. Phosphoamino acld sequence analysls and site dlrected mutagenesis identified Ser 199 as the sole phosphoamino acid in the protein phosphorylated by PKA. Phosphorylation Introduced by PKA resulted in the suppression qf the ablllty of proteln A1 to promote strand annealing in vitro, wlthout any detectable effect on Its nuclelc acld binding capacity. This flndlng indicates that phosphorylation of a single serlne resldue In the C-terminal domain may significantty alter the properties of protein A1.

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© 1993 Oxford University Press

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