Annexin I is phosphorylated in the multivesicular body during the processing of the epidermal growth factor receptor - PubMed (original) (raw)

Annexin I is phosphorylated in the multivesicular body during the processing of the epidermal growth factor receptor

C E Futter et al. J Cell Biol. 1993 Jan.

Abstract

We have previously shown that an active epidermal growth factor receptor (EGF-R) kinase is necessary for efficient sorting of the EGF-R to the lysosome, and we have shown that this occurs in the multivesicular body (MVB), where EGF-R are sorted away from recycling receptors by being removed to the internal vesicles of the MVB. The aim of the present study was to identify substrates of the EGF-R kinase associated with MVBs which might play a role in this sorting process. We used a density shift technique to isolate MVBs and show that the major substrates phosphorylated in vitro within MVBs which contain an active EGF-R kinase are the EGF-R itself and annexin I. Annexin I is associated with both plasma membrane and MVBs in a calcium-independent manner but can be phosphorylated in vitro only in MVBs. Phosphorylation of calcium-independent annexin I in isolated MVBs converts it to a form that requires calcium for membrane association. In cells with an active EGF-R kinase the amount of calcium-independent annexin I in MVBs is reduced, suggesting that a phosphorylation-induced conversion of the calcium independent to the calcium-dependent form also occurs in vivo. Our observations, together with the known properties of annexin I in mediating membrane fusion, suggest that inward vesiculation in MVBs is induced by the EGF-R and is mediated by phosphorylated annexin I.

PubMed Disclaimer

Similar articles

Cited by

References

    1. Cell. 1985 Mar;40(3):619-25 - PubMed
    1. J Cell Biol. 1992 Apr;117(1):203-12 - PubMed
    1. J Cell Biol. 1976 Oct;71(1):159-71 - PubMed
    1. J Cell Biol. 1989 Dec;109(6 Pt 1):2751-60 - PubMed
    1. Cell. 1989 Oct 6;59(1):33-43 - PubMed

Publication types

MeSH terms

Substances

LinkOut - more resources