Expression and Functional Analysis of a Novel Isoform of Gicerin, an Immunoglobulin Superfamily Cell Adhesion Molecule

doi:10.1074/jbc.270.48.28681

Expression and Functional Analysis of a Novel Isoform of Gicerin, an Immunoglobulin Superfamily Cell Adhesion Molecule (*)

From the Department of Pharmacology 1, Osaka University Medical School, 2-2 Yamadaoka, Suita, Osaka 565, Japan

^§ To whom correspondence should be addressed:
Dept. of Pharmacology 1, Osaka Universit Medical School, 2-2 Yamadaoka, Suita, Osaka 565, Japan.
Tel.: 81-6-879-3521; Fax: 81-6-879-3529.

Abstract

We have cloned a novel cDNA of gicerin, a cell adhesion molecule belonging to the immunoglobulin superfamily. Both gicerin isoforms share the same extracellular domain, which has five immunoglobulin-like loop structures and a transmembrane domain as s-gicerin, but differ in the cytoplasmic tail domain. As the newly identified form has a larger cytoplasmic domain than the previously reported form, we refer to them as l-gicerin and s-gicerin, respectively. l-gicerin is transcribed from a distinct mRNA containing an inserted sequence not found in s-gicerin mRNA which caused a frameshift for the coding region for a cytoplasmic domain. Previous studies demonstrated that gicerin showed a doublet band of 82 and 90 kDa in chicken gizzard smooth muscle. We report that the 82-kDa protein corresponds to s-gicerin and the 90-kDa protein to l-gicerin. We also found that the two gicerin isoforms are expressed differentially in the developing nervous system. Functional analysis of these gicerin isoforms in stable transfectants revealed that they had differ in their homophilic adhesion properties, as well as in heterophilic cell adhesion assayed with neurite outgrowth factor. In addition, these isoforms have neurite-promoting activity by their homophilic adhesion, but differ in their ability to promote neurite outgrowth.

Footnotes

↵(*) This work was supported by a grant-in-aid for Scientific Research from the Ministry of Education, Science, and Culture of Japan. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank(TM)/EMBL Data Bank with accession number(s) D49849 [GenBank](l-gicerin).
↵¹ The abbreviations used are:

MAG

myelin-associated glycoprotein

NOF

neurite outgrowth factor

RT-PCR

reverse transcription polymerase chain reaction

PAGE

polyacrylamide gel electrophoresis

FCS

fetal calf serum

CG

ciliary ganglion

bp

base pair(s)

NCAM

neural cell adhesion molecule.
- Received July 17, 1995.
- Revision received September 21, 1995.