FET4 Antibody

Introduction to FET4 Antibody

The FET4 antibody is a immunological tool used to detect and study the FET4 protein, a low-affinity iron transporter in Saccharomyces cerevisiae. FET4 facilitates the uptake of divalent metals, including Fe²⁺ and toxic cadmium ions, and is regulated by cellular iron levels and oxidative stress pathways . Antibodies against FET4 have been critical in elucidating its structural properties, membrane localization, and role in metal homeostasis .

Antibody Development

FET4 antibodies (e.g., anti-L1, anti-N, anti-L5) were generated against epitopes in the N-terminal, loop 1 (between M1–M2), and loop 5 (between M5–M6) regions. These antibodies confirmed FET4’s plasma membrane localization via immunofluorescence and subcellular fractionation .

Role in Iron Transport

• Kinetic parameters: The low-affinity Fe²⁺ uptake system mediated by FET4 has an apparent Kₘ of 25–30 μM and Vₘₐₓ of 1.2 nmol/min/mg protein .

• Mutations: Substitutions in transmembrane residues (e.g., H³⁵⁴A) alter transport kinetics, confirming direct metal interaction .

Table 1: Effects of FET4 Mutations on Fe²⁺ Uptake4

Regulation by Oxidative Stress

• Yap1-Rox1 axis: The transcription factor Yap1 represses FET4 via Rox1, a hypoxic repressor, to limit cadmium uptake. Deletion of YAP1 increases FET4 expression and cadmium sensitivity .

• Post-transcriptional control: In yap1 or rox1 mutants, the exoribonuclease Xrn1 degrades FET4 mRNA to compensate for derepression .

Immunoblot Protocols

FET4-HA fusion proteins (tagged at the C-terminus) are used to monitor protein levels under cadmium stress. Key steps include:

1. Protein extraction: Cells treated with 25 μM CdCl₂ are lysed, and total proteins are resolved via SDS-PAGE .

2. Detection: Anti-HA antibodies (e.g., Roche horseradish peroxidase-conjugated IgG) confirm FET4 expression changes .

Functional Studies

• Metal toxicity: FET4 antibodies validate its role in cadmium accumulation, showing yap1Δ mutants have 2.5-fold higher intracellular cadmium .

• Subcellular localization: Immunofluorescence confirms FET4’s plasma membrane localization, critical for its transport activity .

Significance and Future Directions

FET4 antibodies have advanced understanding of divalent metal transport mechanisms and their regulation under stress. Future studies may explore:

• Therapeutic potential: Targeting FET4 homologs in pathogenic fungi.

• Structural biology: Cryo-EM studies to resolve FET4’s metal-binding pockets.