Two species of human CRK cDNA encode proteins with distinct biological activities.

Abstract

Two distinct human CRK cDNAs, designated CRK-I and CRK-II, were isolated from human embryonic lung cells by polymerase chain reaction and by screening of a human placenta cDNA library, respectively. CRK-I differed from CRK-H in that it lacked a 170-nucleotide sequence, suggesting that CRK-I and CRK-II were the products of alternative splicing. The amino acid sequences deduced from these two cDNAs differed in the carboxyl termini and contained one SH2 and either one or two SH3 domains. RNase cells showed that the former encoded the 28-kDa protein and the latter encoded the 40-and 42-kDa proteins. All human cell lines so far examined expressed the 40-kDa protein; however, expression of the 28-and the 42-kDa proteins was variable. In a comparison of the biological activity of the two human CRK proteins, both proteins were stably expressed in rat 3Y1 cells. All cell lines expressing CRK-I protein showed altered morphology, proliferated in soft agar, and grew as massive tumors in nude mice. Although CRK-II-expressing cells showed a slight morphologic change, they did not make colonies in soft agar or grow in nude mice. These results demonstrate that the two species of human CRK cDNA encode proteins which differ in their biological activities.

Identification of Tyr-762 in the platelet-derived growth factor α-receptor as the binding site for Crk proteins

“…Searches in a data base revealed that the analysed partial amino acid sequences of p27, p38 and p40 were identical to internal sequences found in human CrkI, CrkII and CrkL proteins, respectively (Figure 1c). The Crk family of adaptor molecules consists of CrkI with one SH2 and one SH3 domains and CrkII and CrkL with one SH2 and two SH3 domains each (Matsuda et al, 1992;Reichman et al, 1992;ten Hoeve et al, 1993). CrkI and CrkII are di erent splice variants of the same gene, whereas CrkL is derived from a distinct gene.…”

Involvement of adaptor protein Crk in malignant feature of human ovarian cancer cell line MCAS

“…The contribution of c-Crk to tumorigenesis was suggested by an earlier study showing that c-Crk-I induced anchorage-independent growth of rodent fibroblasts together with tyrosine-phosphorylation of p130 Cas (Matsuda et al, 1992b). We previously reported that Crk is overexpressed in human cancers including various carcinomas and sarcomas (Nishihara et al, 2002c).…”

“…Since the isolation of mammalian homologues of viral Crk, such as c-Crk-I and c-Crk-II (Matsuda et al, 1992b), Crk has been shown to transmit signals under various stimuli including epidermal growth factor, neurotrophic growth factor and fibroblast growth factor (Tanaka et al, 1993;Feller, 2001). c-Crk-II possesses one SH2 domain at the N-terminus and two SH3 domains, wheras its alternative splicing product c-Crk-I is composed of the SH2 domain and a single SH3 domain.…”

Development of highly selective SH3 binding peptides for Crk and CRKL which disrupt Crk-complexes with DOCK180, SoS and C3G

“…SH2 and SH3 domains are not only found as accessory protein interaction domains in various enzymes and structural proteins, they are also utilised as virtually exclusive building blocks of a class of signalling proteins known as the SH2/SH3 adapter family. One member of this protein family, c-Crk II, is composed of an N-terminal SH2 domain, followed by two SH3 domains (Reichman et al, 1992;Matsuda et al, 1992). The SH3 domains are separated by a`spacer region' which contains a protein conformation-regulating tyrosine residue (Feller et al, 1994a;Rosen et al, 1995).…”