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#KDEL receptor

2 public questions tagged with this topic.

Protein Sorting and Trafficking

How does the KDEL receptor regulate protein retrieval?

ER lumen contains chaperones BiP HSPA5, Grp94 HSP90B1, PDI family, calreticulin that may leak into Golgi during non-selective bulk flow; retention therefore relies on active retrieval not static retention. Soluble residents carry C-terminal KDEL tetrapeptide Lys-Asp-Glu-Leu or variant HDEL. If they escape to cis-Golgi beyond, KDEL receptors family of seven-transmembrane proteins Erd2 in yeast KDELR1-3 in mammals concentrated in Golgi and ERGIC recognize tetrapeptide. Binding strongly pH dependent because histidine residues protonate at mildly acidic Golgi lumen pH 6.0-6.2 stabilizing interacti

Ref: Alberts et al., MBC Chapter 13: KDEL receptor pH-dependent retrieval to ER via COPI.

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Protein Sorting and Trafficking

The ER retention signal KDEL is recognized by:

Retention and retrieval of escaped ER resident proteins depends on pH-sensitive recognition of C-terminal retention signal by cycling receptor Erd2 localized predominantly in cis-Golgi and ER-Golgi intermediate compartment but trafficking constitutively. Human KDEL receptor family comprises three isoforms KDELR1-3 sharing seven-transmembrane architecture with lumenal binding pocket formed by polar residues and conserved histidine that at acidic pH around 6.2 characteristic of Golgi protonates enhancing affinity for Lys-Asp-Glu-Leu tetrapeptide and variants HDEL, RDEL. Ligand binding induces co

Ref: Munro & Pelham, Cell 48: 1987, KDEL Receptor Erd2 Recognizing KDEL Signal.

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