Ultrastructural analysis of the organization and distribution of insulin receptors on the surface of 3T3-L1 adipocytes: Rapid microaggregation and migration of occupied receptors

R. M. Smith, M. H. Cobb, O. M. Rosen, L. Jarett

Research output: Contribution to journalArticle

24 Citations (Scopus)

Abstract

Monomeric ferritin-insulin and high-resolution electron microscopic analysis were used to study the organization, distribution, and movement of insulin receptors on differentiated 3T3-L1 adipocytes. Analysis of the binding to prefixed cells showed that insulin initially occupied single and paired receptors preferentially located on microvilli. The majority of - receptors (60%) were found as single molecules and 30% were pairs. In 1 min at 37° C, 50% of the receptors on nonfixed cells were found on the intervillous plasma membrane and more than 70% of the total receptors had microaggregated. By 30 min only 7% of the receptors were single or paired molecules on microvilli. The majority were on the intervillous membrane, with 95% of those receptors in groups. The receptor groups on the intervillous plasma membrane could be found in both noncoated invaginations and coated pits. The concentration of occupied receptors in the noncoated invaginations and the coated pits was similar; however, ten times more noncoated invaginations than coated pits contained occupied insulin receptors. The observations in this study contrast with those reported on rat adipocytes using identical techniques (Jarett and Smith, 1977). Insulin receptors on adipocytes were initially grouped and randomly distributed over the entire cell surface and did not microaggregate into larger groups. Insulin receptors on rat adipocytes were found in noncoated invaginations but were excluded from the coated pits. The differences in the organization and behavior of the insulin receptor between rat and 3T3-L1 adipocytes suggest that the mechanisms regulating the initial organization of insulin receptors and the aggregation of occupied receptors may be controlled by tissue-specific processes. Since both of these cell types are equally insulin sensitive, the differences in the initial organization and distribution of the insulin receptors on the cell surface may not be related to the sensitivity or biological responsiveness of these cells to insulin but may affect other processes such as receptor regulation and internalization. On the other hand, the microaggregates of occupied receptors on both cell types may relate to biological responsiveness.

Original languageEnglish (US)
Pages (from-to)167-179
Number of pages13
JournalJournal of Cellular Physiology
Volume123
Issue number2
StatePublished - 1985

Fingerprint

Insulin Receptor
Adipocytes
Insulin
Rats
Cell membranes
Microvilli
Receptor Aggregation
Cell Membrane
Molecules
Ferritins
Agglomeration
Electrons
Tissue
Membranes

ASJC Scopus subject areas

  • Cell Biology
  • Clinical Biochemistry
  • Physiology

Cite this

@article{449f4abf883347b3b695efa92b927c1c,
title = "Ultrastructural analysis of the organization and distribution of insulin receptors on the surface of 3T3-L1 adipocytes: Rapid microaggregation and migration of occupied receptors",
abstract = "Monomeric ferritin-insulin and high-resolution electron microscopic analysis were used to study the organization, distribution, and movement of insulin receptors on differentiated 3T3-L1 adipocytes. Analysis of the binding to prefixed cells showed that insulin initially occupied single and paired receptors preferentially located on microvilli. The majority of - receptors (60{\%}) were found as single molecules and 30{\%} were pairs. In 1 min at 37° C, 50{\%} of the receptors on nonfixed cells were found on the intervillous plasma membrane and more than 70{\%} of the total receptors had microaggregated. By 30 min only 7{\%} of the receptors were single or paired molecules on microvilli. The majority were on the intervillous membrane, with 95{\%} of those receptors in groups. The receptor groups on the intervillous plasma membrane could be found in both noncoated invaginations and coated pits. The concentration of occupied receptors in the noncoated invaginations and the coated pits was similar; however, ten times more noncoated invaginations than coated pits contained occupied insulin receptors. The observations in this study contrast with those reported on rat adipocytes using identical techniques (Jarett and Smith, 1977). Insulin receptors on adipocytes were initially grouped and randomly distributed over the entire cell surface and did not microaggregate into larger groups. Insulin receptors on rat adipocytes were found in noncoated invaginations but were excluded from the coated pits. The differences in the organization and behavior of the insulin receptor between rat and 3T3-L1 adipocytes suggest that the mechanisms regulating the initial organization of insulin receptors and the aggregation of occupied receptors may be controlled by tissue-specific processes. Since both of these cell types are equally insulin sensitive, the differences in the initial organization and distribution of the insulin receptors on the cell surface may not be related to the sensitivity or biological responsiveness of these cells to insulin but may affect other processes such as receptor regulation and internalization. On the other hand, the microaggregates of occupied receptors on both cell types may relate to biological responsiveness.",
author = "Smith, {R. M.} and Cobb, {M. H.} and Rosen, {O. M.} and L. Jarett",
year = "1985",
language = "English (US)",
volume = "123",
pages = "167--179",
journal = "Journal of Cellular Physiology",
issn = "0021-9541",
publisher = "Wiley-Liss Inc.",
number = "2",

}

TY - JOUR

T1 - Ultrastructural analysis of the organization and distribution of insulin receptors on the surface of 3T3-L1 adipocytes

T2 - Rapid microaggregation and migration of occupied receptors

AU - Smith, R. M.

AU - Cobb, M. H.

AU - Rosen, O. M.

AU - Jarett, L.

PY - 1985

Y1 - 1985

N2 - Monomeric ferritin-insulin and high-resolution electron microscopic analysis were used to study the organization, distribution, and movement of insulin receptors on differentiated 3T3-L1 adipocytes. Analysis of the binding to prefixed cells showed that insulin initially occupied single and paired receptors preferentially located on microvilli. The majority of - receptors (60%) were found as single molecules and 30% were pairs. In 1 min at 37° C, 50% of the receptors on nonfixed cells were found on the intervillous plasma membrane and more than 70% of the total receptors had microaggregated. By 30 min only 7% of the receptors were single or paired molecules on microvilli. The majority were on the intervillous membrane, with 95% of those receptors in groups. The receptor groups on the intervillous plasma membrane could be found in both noncoated invaginations and coated pits. The concentration of occupied receptors in the noncoated invaginations and the coated pits was similar; however, ten times more noncoated invaginations than coated pits contained occupied insulin receptors. The observations in this study contrast with those reported on rat adipocytes using identical techniques (Jarett and Smith, 1977). Insulin receptors on adipocytes were initially grouped and randomly distributed over the entire cell surface and did not microaggregate into larger groups. Insulin receptors on rat adipocytes were found in noncoated invaginations but were excluded from the coated pits. The differences in the organization and behavior of the insulin receptor between rat and 3T3-L1 adipocytes suggest that the mechanisms regulating the initial organization of insulin receptors and the aggregation of occupied receptors may be controlled by tissue-specific processes. Since both of these cell types are equally insulin sensitive, the differences in the initial organization and distribution of the insulin receptors on the cell surface may not be related to the sensitivity or biological responsiveness of these cells to insulin but may affect other processes such as receptor regulation and internalization. On the other hand, the microaggregates of occupied receptors on both cell types may relate to biological responsiveness.

AB - Monomeric ferritin-insulin and high-resolution electron microscopic analysis were used to study the organization, distribution, and movement of insulin receptors on differentiated 3T3-L1 adipocytes. Analysis of the binding to prefixed cells showed that insulin initially occupied single and paired receptors preferentially located on microvilli. The majority of - receptors (60%) were found as single molecules and 30% were pairs. In 1 min at 37° C, 50% of the receptors on nonfixed cells were found on the intervillous plasma membrane and more than 70% of the total receptors had microaggregated. By 30 min only 7% of the receptors were single or paired molecules on microvilli. The majority were on the intervillous membrane, with 95% of those receptors in groups. The receptor groups on the intervillous plasma membrane could be found in both noncoated invaginations and coated pits. The concentration of occupied receptors in the noncoated invaginations and the coated pits was similar; however, ten times more noncoated invaginations than coated pits contained occupied insulin receptors. The observations in this study contrast with those reported on rat adipocytes using identical techniques (Jarett and Smith, 1977). Insulin receptors on adipocytes were initially grouped and randomly distributed over the entire cell surface and did not microaggregate into larger groups. Insulin receptors on rat adipocytes were found in noncoated invaginations but were excluded from the coated pits. The differences in the organization and behavior of the insulin receptor between rat and 3T3-L1 adipocytes suggest that the mechanisms regulating the initial organization of insulin receptors and the aggregation of occupied receptors may be controlled by tissue-specific processes. Since both of these cell types are equally insulin sensitive, the differences in the initial organization and distribution of the insulin receptors on the cell surface may not be related to the sensitivity or biological responsiveness of these cells to insulin but may affect other processes such as receptor regulation and internalization. On the other hand, the microaggregates of occupied receptors on both cell types may relate to biological responsiveness.

UR - http://www.scopus.com/inward/record.url?scp=0021999827&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0021999827&partnerID=8YFLogxK

M3 - Article

C2 - 3920228

AN - SCOPUS:0021999827

VL - 123

SP - 167

EP - 179

JO - Journal of Cellular Physiology

JF - Journal of Cellular Physiology

SN - 0021-9541

IS - 2

ER -