1: Gene. 1998 Feb 27;208(2):117-22. 

Further characterization of the murine collagenase (type IVB) gene promoter and
analysis of mRNA expression in murine tissues.

Roach J, Choi SJ, Schaub RL, Leach RJ, Roodman GD, Reddy SV.

Department of Medicine and Hematology, University of Texas Health Science
Center, San Antonio 78284-7880, USA.

The collagenase B type IV (Col4B) gene is highly expressed in the osteoclast,
the primary bone-resorbing cell. However, factors that regulate expression of
the Col4B gene are not well characterized. A murine P1 genomic clone containing
a 94 kb sequence insert which contains the Col4B gene was isolated. A 4 kb EcoR1
DNA fragment containing the 5' flanking sequence of the gene was further
subcloned and restriction mapped. Putative transcription factors such as SRY,
Lyf-1, and GATA1 and 2, binding motifs were identified by sequence analysis in
this promoter region. Enhancer and suppressor regions were mapped by transient
expression of Col4B gene promoter deletion mutant-luciferase reporter gene
constructs in HepG2 cells. Col4B mRNA expression in different murine tissues was
analyzed by reverse transcription-polymerase chain reaction and demonstrated
high levels of expression in bone, clavaria, spleen and thymus. This promoter
provides a valuable tool for targeting gene expression to the osteoclast.

PMID: 9524243 [PubMed - indexed for MEDLINE]


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2: Biochem J. 1996 Jan 1;313 ( Pt 1):245-51. 

PEST motifs are not required for rapid calpain-mediated proteolysis of c-fos
protein.

Carillo S, Pariat M, Steff A, Jariel-Encontre I, Poulat F, Berta P, Piechaczyk
M.

Institut de Genetique Moleculaire de Montpellier/UMR 9942, France.

Cytoplasmic degradation of c-fos protein is extremely rapid. Under certain
conditions, it is a multi-step process initiated by calcium-dependent and
ATP-independent proteases called calpains. PEST motifs are peptide regions rich
in proline, glutamic acid/aspartic acid and serine/threonine residues, commonly
assumed to constitute built-in signals for rapid recognition by intracellular
proteases and particularly by calpains. Using a cell-free degradation assay and
site-directed mutagenesis, we report here that the three PEST motifs of c-fos
are not required for rapid cleavage by calpains. Testing the susceptibility of
PEST motif-bearing and non-bearing transcription factors including GATA1, GATA3,
Myo D, c-erbA, Tal-1 and Sry, demonstrates that PEST sequences are neither
necessary nor sufficient for specifying degradation of other proteins by
calpains. This conclusion is strengthened by the observation that certain
proteins, reportedly known to be cleavable by calpains, are devoid of PEST
motifs.

PMID: 8546691 [PubMed - indexed for MEDLINE]


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