Identification of a major cyclic AMP-dependent protein kinase A phosphorylation site within the cytoplasmic tail of the low-density lipoprotein receptor-related protein: Implication for receptor-mediated endocytosis

Y. Li, P. Van Kerkhof, M. P. Marzolo, G. J. Strous, G. Bu

Research output: Contribution to journalArticle

62 Scopus citations

Abstract

The low-density lipoprotein (LDL) receptor-related protein (LRP) is a multiligand endocytic receptor that belongs to the LDL receptor family. Recently, studies have revealed new roles of LDL receptor family members as transducers of extracellular signals. Our previous studies have demonstrated LRP phosphorylation within its cytoplasmic tail, but the nature of LRP phosphorylation and its potential function was unknown. In the present study using both in vivo and in vitro analysis, we found that LRP phosphorylation is mediated by the cAMP-dependent protein kinase A (PKA). Using site-directed mutagenesis and LRP minireceptor constructs, we further identified the predominant LRP phosphorylation site at serine 76 of its cytoplasmic tail. Finally, we demonstrated that mutations of serine 76, which abolish LRP phosphorylation by PKA, result in a decrease in the initial endocytosis rate of LRP and a lower efficiency in delivery of ligand for degradation. Thus, the role of PKA phosphorylation of LRP in receptor-mediated endocytosis may provide a mechanism by which the endocytic function of LRP can be regulated by external signals.

Original languageEnglish (US)
Pages (from-to)1185-1195
Number of pages11
JournalMolecular and cellular biology
Volume21
Issue number4
DOIs
StatePublished - 2001

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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