Systems Approach to Therapeutics Design

Lao, Bert J.; Kamei, Daniel T.

doi:10.1007/978-1-59745-525-1_8

Cited by 1 publication

(1 citation statement)

References 13 publications

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“…On average, each TfR molecule spends less than 3 min on the cell surface before being internalized again (27). Although the commonly accepted model of iron delivery to tissues implies that the apo-hTf/TfR complex dissociation occurs within seconds upon its exposure to the neutral environment at the cell surface (28), our data indicate that the protein may remain bound to TfR for extended periods of time (vide supra).…”

Section: Discussionmentioning

confidence: 68%

Noncanonical interactions between serum transferrin and transferrin receptor evaluated with electrospray ionization mass spectrometry

Leverence

Mason

Kaltashov

2010

Proc. Natl. Acad. Sci. U.S.A.

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The primary route of iron acquisition in vertebrates is the transferrin receptor (TfR) mediated endocytotic pathway, which provides cellular entry to the metal transporter serum transferrin (Tf). Despite extensive research efforts, complete understanding of Tf-TfR interaction mechanism is still lacking owing to the complexity of this system. Electrospray ionization mass spectrometry (ESI MS) is used in this study to monitor the protein/receptor interaction and demonstrate the ability of metal-free Tf to associate with TfR at neutral pH. A set of Tf variants is used in a series of competition and displacement experiments to bracket TfR affinity of apo-Tf at neutral pH (0.2-0.6 μM). Consistent with current models of endosomal iron release from Tf, acidification of the protein solution results in a dramatic change of binding preferences, with apo-Tf becoming a preferred receptor binder. Contrary to the current models implying that the apo-Tf/TfR complex dissociates almost immediately upon exposure to the neutral environment at the cell surface, our data indicate that this complex remains intact. Iron-loaded Tf displaces apo-Tf from TfR, making it available for the next cycle of iron binding, transport and delivery to tissues. However, apo-Tf may still interfere with the cellular uptake of engineered Tf molecules whose TfR affinity is affected by various modifications (e.g., conjugation to cytotoxic molecules). This work also highlights the great potential of ESI MS as a tool capable of providing precise details of complex protein-receptor interactions under conditions that closely mimic the environment in which these encounters occur in physiological systems.metalloprotein | protein interaction

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Section: Discussionmentioning

confidence: 68%