Name: ProSpec Bio Recombinant Human Cystatin 4, Sf9
Brand: ProSpec Bio
SKU: PSB-PRO-2250
Availability: InStock

<h2>What are recombinant proteins in this category?</h2>
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Proteins in this category are unlabeled, base recombinant products covering cytokines and growth factors that drive cell signaling and development, enzymes used for catalytic or structural studies, and other structural or functional proteins, produced using bacterial, insect cell, or mammalian expression systems depending on the modifications a given target requires.
These are distinct from the fluorescently labeled and biotin/Fc-fusion conjugated formats covered in sibling subcategories, serving applications like cell culture supplementation, enzymatic assays, and biochemical characterization that don't need a built-in label or capture handle.
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<h2 dir="ltr">What you will find:</h2>
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Bioactive Cellular Ligands: High-purity structural configurations engineered to interact predictably with cell surface receptors and initiate target signaling cascades.
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Analytical Reference Standards: Standardized protein formulations prepared to establish accurate quantitative baselines and molecular weight controls in gel electrophoresis.
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Functional Enzymatic Catalysts: Highly stable macromolecular proteins optimized to maintain specific kinetic activity and drive target biochemical transformations.
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<h2>How to choose recombinant proteins</h2>
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Confirm the expression system matches your protein's modification needs
A protein expressed in bacteria will lack glycosylation and certain folding assistance that a mammalian or insect-cell-expressed version of the same protein would have, so confirming which expression system was used, and whether that matters for your application, is an important first check.
Check bioactivity and purity specifications for functional studies
Recombinant proteins intended for functional or signaling studies are typically tested in an appropriate biological assay to confirm activity meets a defined specification, and checking this bioactivity data, alongside purity by SDS-PAGE or similar methods, matters more for functional work than for applications using the protein purely as a loading control or standard.
Decide whether an animal-free or GMP-grade product matters for your application
Animal-free recombinant proteins reduce contamination risk relevant to certain cell culture or translational research applications, while GMP-grade proteins support a path toward future clinical-adjacent work, though most basic academic research can use standard research-grade product.
Confirm whether your target needs a purification or epitope tag
A tagged version of a protein, such as one with a polyhistidine or epitope tag, can simplify downstream detection or further purification, while an untagged version may be preferred when the tag itself could interfere with a specific binding or functional assay.
Plan for appropriate storage and handling to preserve activity
Recombinant proteins generally require careful storage, often with aliquoting to avoid repeated freeze-thaw cycles, since repeated freezing and thawing can degrade protein structure and reduce measured bioactivity over time.
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<h2>Specifications context</h2>
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Recombinant protein products are commonly tested for biological activity in an appropriate assay system before release, with lot-to-lot consistency evaluated specifically so that researchers don't need to re-validate reproducibility across different production batches for an established product.
As of 2026, animal-free and GMP-grade recombinant protein options continue to expand alongside standard research-grade catalogs, supporting researchers whose work may eventually need a translational or clinical-adjacent pathway without switching suppliers.
<a href="https://mbpinc.net/contact-us">Contact the helpful team</a> at MBP today to request a quote.

Proteins

ProSpec Bio

Key Specifications

ProSpec Bio Recombinant Human Cystatin 4, Sf9

Recombinant Human Cystatin 4, Sf9 by ProSpec Bio is a recombinant human CST4 protein expressed in Sf9 insect cells (aa 21–141, C-terminal His tag, 15.4 kDa, >95% pure), supplied as a solution. Sizes: 2 µg (pro-2250), 10 µg (pro-2250-1), 1 mg (pro-2250-2). Available from MBP, a registered vendor at leading US research institutions.