Contrasting patterns of protein phosphorylation in human normal and Alzheimer brain: Focus on protein kinase C and protein F1 GAP-43

Jose C. Florez*, Robert B. Nelson, Aryeh Routtenberg

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

20 Scopus citations

Abstract

We introduce a new procedure to study kinase substrates in postmortem human brain. By adding purified exogenous protein kinase C (PKC) and the phospholipid phosphatidylserine to brain homogenates in vitro we are able to analyze PKC substrates. A human 53-kDa phosphoprotein is described that appears to be homologous to rat and monkey protein F1 (GAP-43). This identity is based on molecular weight, isoelectric point, phosphorylation by exogenous protein kinase C, enhancement of its phosphorylation by three activators (phospholipids, calcium and phorbol esters), phosphopeptide maps, and cross-reactivity with an antibody raised against rat protein F1. Protein F1 is a PKC substrate associated with synaptic plasticity and nerve growth. Its phosphorylation in rat brain has been correlated with long-term potentiation, an electrophysiological model of memory. In the present study of normal brain, human protein F1 shows an occipitotemporal in vitro phosphorylation gradient. This is consistent with previous observations in nonhuman primates. This gradient is less pronounced in Alzheimer's disease (AD). Changes in the in vitro phosphorylation pattern of three other non-PKC substrates in Alzheimer's disease, including one with characteristics similar to microtubule-associated protein tau, are also reported. These results suggest that protein phosphorylation can be studied in postmortem human brain and that PKC-mediated phosphorylation of protein F1, already linked to synaptic plasticity and memory, may be altered in AD.

Original languageEnglish (US)
Pages (from-to)264-272
Number of pages9
JournalExperimental Neurology
Volume112
Issue number3
DOIs
StatePublished - Jun 1991

ASJC Scopus subject areas

  • Neurology
  • Developmental Neuroscience

Fingerprint Dive into the research topics of 'Contrasting patterns of protein phosphorylation in human normal and Alzheimer brain: Focus on protein kinase C and protein F1 GAP-43'. Together they form a unique fingerprint.

Cite this