Kremen2, Recombinant, Rat (Kringle-containing Protein Marking the Eye and the Nose, Kringle Domain-containing Transmembrane Protein 2)

Kremen (Kringle-containing protein marking the eye and the nose) proteins are type I transmembrane proteins that contain extracellular kringle, WSC and CUB domains, and an intracellular region with no conserved motifs (1). Two related molecules, Kremen-1 and -2, have been identified. Kremens bind with high affinity to a subset of the secreted Dickkopf proteins (Dkk-1, -2, and -4) to modulate the canonical Wnt signaling pathway (2). This pathway is transduced by a ternary receptor complex composed of Wnt, the seven-transmembrane domain receptor Frizzled, and the LDL-receptor-related protein 5/6 (LRP5/6) coreceptor (3, 4). Dkk-1 and -4 bind directly to the LRP5/6 coreceptor to antagonize the canonical Wnt/b-catenin signaling pathway. The planar cell polarity (PCP) signaling pathway is not affected as it does not involve LRP5/6 (2). In contrast, Dkk-3 has no effect on Wnt signaling. Dkk-2 can function either as an LRP agonist or antagonist, depending on whether or not the cell expresses Kremen (5). Kremen cooperates with Dkk to antagonize Wnt signaling via formation of a Kremen-Dkk-LRP ternary complex which is internalized and cleared from the cell surface (4). Binding requires all three extracellular domains of Kremen, and the second cysteine-rich domain of Dkk (4). The predicted rat Kremen-2 cDNA encodes a 490 aa glycosylated protein with a 51 aa signal peptide, a 340 aa extracellular domain, a 24 aa transmembrane domain, and a 75 aa cytoplasmic domain. Within the ECD, rat Kremen-2 shares 91% and 98% aa sequence identity with human and mouse Kremen-2, respectively, and 46% with rat Kremen-1.\n\nA DNA sequence encoding the extracellular domain of rat Kremen-2 (Gly 53-Arg 395; Accession # XP_220206) was fused with a six-histidine tag at the C-terminus. The protein was expressed in a mouse myeloma cell line, NS0.\n\nCalculated molecular mass of ~ 37.5kD. As a result of glycosylation, recombinant rat Kremen-2 migrates as an ~ 45-55kD protein in SDS-PAGE under reducing conditions.\n\nActivity: Measured by its ability to bind biotinylated rhDkk-1.\n\nStorage and Stability:\nLyophilized powder may be stored at 4 degrees C for short-term only. Reconstitute to nominal volume by adding sterile PBS and store at -20 degrees C. Reconstituted product is stable for 12 months at -20 degrees C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.

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SPECIFICATIONS

Catalog Number

K5002-02

Size

25ug

Form

Supplied as a lyophilized powder in PBS. Reconstitute with PBS to (same/more than)100ug/ml.

Purity

(same/more than) 85%, as determined by SDS-PAGE under reducing conditions and visualized by silver stain.\nEndotoxin: (same/less than) 1EU/1ug.

References

1. Nakamura, T. et al., 2001, Biochim. Biophys. Acta 1518:63.\n2. Niehrs, C., 2006, Oncogene 25:7469.\n3. Davidson G. et al., 2002, Development 129:5587.\n4. Mao, B. et al., 2002, Nature 417:664.\n5. Mao, B. and C. Niehrs, 2003, Gene 302:179.